diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.cpp.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.cpp.mustache
index 083477d37e9b..090672ed68ca 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.cpp.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.cpp.mustache
@@ -7,6 +7,9 @@
 #include <QUrl>
 #include <QUuid>
 #include <QtGlobal>
+#include <QtAlgorithms>
+
+#include <utility>
 {{#contentCompression}}
 #include <zlib.h>{{/contentCompression}}
 
@@ -20,7 +23,7 @@ namespace {{this}} {
     initialize();
 }
 
-{{prefix}}HttpRequestInput::{{prefix}}HttpRequestInput(QString v_url_str, QString v_http_method) {
+{{prefix}}HttpRequestInput::{{prefix}}HttpRequestInput(const QString &v_url_str, const QString &v_http_method) {
     initialize();
     url_str = v_url_str;
     http_method = v_http_method;
@@ -32,11 +35,11 @@ void {{prefix}}HttpRequestInput::initialize() {
     http_method = "GET";
 }
 
-void {{prefix}}HttpRequestInput::add_var(QString key, QString value) {
+void {{prefix}}HttpRequestInput::add_var(const QString &key, const QString &value) {
     vars[key] = value;
 }
 
-void {{prefix}}HttpRequestInput::add_file(QString variable_name, QString local_filename, QString request_filename, QString mime_type) {
+void {{prefix}}HttpRequestInput::add_file(const QString &variable_name, const QString &local_filename, const QString &request_filename, const QString &mime_type) {
     {{prefix}}HttpFileElement file;
     file.variable_name = variable_name;
     file.local_filename = local_filename;
@@ -58,11 +61,7 @@ void {{prefix}}HttpRequestInput::add_file(QString variable_name, QString local_f
 {{prefix}}HttpRequestWorker::~{{prefix}}HttpRequestWorker() {
     QObject::disconnect(&timeOutTimer, &QTimer::timeout, nullptr, nullptr);
     timeOutTimer.stop();
-    for (const auto &item : multiPartFields) {
-        if (item != nullptr) {
-            delete item;
-        }
-    }
+    qDeleteAll(multiPartFields);
 }
 
 QMap<QString, QString> {{prefix}}HttpRequestWorker::getResponseHeaders() const {
@@ -116,10 +115,10 @@ int  {{prefix}}HttpRequestWorker::getHttpResponseCode() const{
     return httpResponseCode;
 }
 
-QString {{prefix}}HttpRequestWorker::http_attribute_encode(QString attribute_name, QString input) {
+QString {{prefix}}HttpRequestWorker::http_attribute_encode(const QString &attribute_name, const QString &input) {
     // result structure follows RFC 5987
     bool need_utf_encoding = false;
-    QString result = "";
+    QString result;
     QByteArray input_c = input.toLocal8Bit();
     char c;
     for (int i = 0; i < input_c.length(); i++) {
@@ -143,7 +142,7 @@ QString {{prefix}}HttpRequestWorker::http_attribute_encode(QString attribute_nam
         return QString("%1=\"%2\"").arg(attribute_name, result);
     }
 
-    QString result_utf8 = "";
+    QString result_utf8;
     for (int i = 0; i < input_c.length(); i++) {
         c = input_c.at(i);
         if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
@@ -178,7 +177,7 @@ void {{prefix}}HttpRequestWorker::execute({{prefix}}HttpRequestInput *input) {
 
     // prepare request content
 
-    QString boundary = "";
+    QString boundary;
 
     if (input->var_layout == ADDRESS || input->var_layout == URL_ENCODED) {
         // variable layout is ADDRESS or URL_ENCODED
@@ -186,7 +185,7 @@ void {{prefix}}HttpRequestWorker::execute({{prefix}}HttpRequestInput *input) {
         if (input->vars.count() > 0) {
             bool first = true;
             isFormData = true;
-            for (QString key : input->vars.keys()) {
+            for (const QString &key : input->vars.keys()) {
                 if (!first) {
                     request_content.append("&");
                 }
@@ -208,11 +207,11 @@ void {{prefix}}HttpRequestWorker::execute({{prefix}}HttpRequestInput *input) {
         boundary = QString("__-----------------------%1%2")
                             .arg(QDateTime::currentSecsSinceEpoch())
                             .arg(randomGenerator.generate());
-        QString boundary_delimiter = "--";
-        QString new_line = "\r\n";
+        const QString boundary_delimiter = "--";
+        const QString new_line = "\r\n";
 
         // add variables
-        for (QString key : input->vars.keys()) {
+        for (const QString &key : input->vars.keys()) {
             // add boundary
             request_content.append(boundary_delimiter.toUtf8());
             request_content.append(boundary.toUtf8());
@@ -314,7 +313,7 @@ void {{prefix}}HttpRequestWorker::execute({{prefix}}HttpRequestInput *input) {
         request.setSslConfiguration(*{{prefix}}HttpRequestWorker::sslDefaultConfiguration);
     }
     request.setRawHeader("User-Agent", "{{httpUserAgent}}{{^httpUserAgent}}OpenAPI-Generator/{{apiVersion}}/cpp-qt{{/httpUserAgent}}");
-    for (QString key : input->headers.keys()) { request.setRawHeader(key.toStdString().c_str(), input->headers.value(key).toStdString().c_str()); }
+    for (const QString &key : input->headers.keys()) { request.setRawHeader(key.toStdString().c_str(), input->headers.value(key).toStdString().c_str()); }
 
     if (request_content.size() > 0 && !isFormData && (input->var_layout != MULTIPART)) {
         if (!input->headers.contains("Content-Type")) {
@@ -404,7 +403,7 @@ void {{prefix}}HttpRequestWorker::process_response(QNetworkReply *reply) {
     QString contentTypeHdr;
     QString contentEncodingHdr;
 
-    for(auto hdr: getResponseHeaders().keys()){
+    for(const auto &hdr: getResponseHeaders().keys()){
         if(hdr.compare(QString("Content-Disposition"), Qt::CaseInsensitive) == 0){
             contentDispositionHdr = getResponseHeaders().value(hdr);
         }
@@ -422,7 +421,7 @@ void {{prefix}}HttpRequestWorker::process_response(QNetworkReply *reply) {
             !contentTypeHdr.isEmpty() ? contentTypeHdr.split(QString(";"), Qt::SkipEmptyParts).first() : QString();
         if ((contentDisposition.count() > 0) && (contentDisposition.first() == QString("attachment"))) {
             QString filename = QUuid::createUuid().toString();
-            for (const auto &file : contentDisposition) {
+            for (const auto &file : std::as_const(contentDisposition)) {
                 if (file.contains(QString("filename"))) {
                     filename = file.split(QString("="), Qt::SkipEmptyParts).at(1);
                     break;
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.h.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.h.mustache
index 4566a9c0b0a3..ecc9ea8e501a 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.h.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/HttpRequest.h.mustache
@@ -41,10 +41,10 @@ public:
     QByteArray request_body;
 
     {{prefix}}HttpRequestInput();
-    {{prefix}}HttpRequestInput(QString v_url_str, QString v_http_method);
+    {{prefix}}HttpRequestInput(const QString &v_url_str, const QString &v_http_method);
     void initialize();
-    void add_var(QString key, QString value);
-    void add_file(QString variable_name, QString local_filename, QString request_filename, QString mime_type);
+    void add_var(const QString &key, const QString &value);
+    void add_file(const QString &variable_name, const QString &local_filename, const QString &request_filename, const QString &mime_type);
 };
 
 class {{prefix}}HttpRequestWorker : public QObject {
@@ -59,7 +59,7 @@ public:
     QString error_str;
 
     QMap<QString, QString> getResponseHeaders() const;
-    QString http_attribute_encode(QString attribute_name, QString input);
+    QString http_attribute_encode(const QString &attribute_name, const QString &input);
     void execute({{prefix}}HttpRequestInput *input);
     static QSslConfiguration *sslDefaultConfiguration;
     void setTimeOut(int timeOutMs);
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/README.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/README.mustache
index 7ce175c627b8..42a12d0ffd89 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/README.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/README.mustache
@@ -83,7 +83,7 @@ void Example::exampleFunction1(){
       connect(&apiInstance, &{{{classname}}}::{{nickname}}Signal, [&]() {
           loop.quit();
       });
-      connect(&apiInstance, &{{{classname}}}::{{nickname}}SignalE, [&](QNetworkReply::NetworkError, QString error_str) {
+      connect(&apiInstance, &{{{classname}}}::{{nickname}}SignalE, [&](QNetworkReply::NetworkError, const QString &error_str) {
           qDebug() << "Error happened while issuing request : " << error_str;
           loop.quit();
       });
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/enum.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/enum.mustache
index 0851c1393d8f..21bb678bbcc3 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/enum.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/enum.mustache
@@ -15,7 +15,7 @@ class {{prefix}}Enum {
 public:
     {{prefix}}Enum() {}
 
-    {{prefix}}Enum(QString jsonString) {
+    {{prefix}}Enum(const QString &jsonString) {
         fromJson(jsonString);
     }
 
@@ -35,7 +35,7 @@ public:
         return obj;
     }
 	
-    virtual void fromJson(QString jsonString) {
+    virtual void fromJson(const QString &jsonString) {
         jstr = jsonString;
     }
 
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/model-body.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/model-body.mustache
index 28e3f674e41a..6055967efcc3 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/model-body.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/model-body.mustache
@@ -12,7 +12,7 @@
 namespace {{this}} {
 {{/cppNamespaceDeclarations}}
 
-{{classname}}::{{classname}}(QString json) {
+{{classname}}::{{classname}}(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -33,7 +33,7 @@ void {{classname}}::initializeModel() {
     m_value = e{{classname}}::INVALID_VALUE_OPENAPI_GENERATED;{{/isEnum}}
 }
 
-void {{classname}}::fromJson(QString jsonString) {
+void {{classname}}::fromJson(const QString &jsonString) {
     {{^isEnum}}QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/model-header.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/model-header.mustache
index 8b4a1a6d4d22..e5f8d67d4aff 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/model-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/model-header.mustache
@@ -27,13 +27,13 @@ namespace {{this}} {
 class {{classname}} : public {{prefix}}{{^isEnum}}Object{{/isEnum}}{{#isEnum}}Enum{{/isEnum}} {
 public:
     {{classname}}();
-    {{classname}}(QString json);
+    {{classname}}(const QString &json);
     ~{{classname}}() override;
 
     QString asJson() const override;
     QJson{{^isEnum}}Object{{/isEnum}}{{#isEnum}}Value{{/isEnum}} asJson{{^isEnum}}Object{{/isEnum}}{{#isEnum}}Value{{/isEnum}}() const override;
     void fromJson{{^isEnum}}Object{{/isEnum}}{{#isEnum}}Value{{/isEnum}}(QJson{{^isEnum}}Object{{/isEnum}}{{#isEnum}}Value{{/isEnum}} json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 {{^isEnum}}{{#vars}}
     {{#deprecated}}Q_DECL_DEPRECATED {{/deprecated}}{{{dataType}}} {{getter}}() const;
     {{#deprecated}}Q_DECL_DEPRECATED {{/deprecated}}void {{setter}}(const {{{dataType}}} &{{name}});
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.cpp.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.cpp.mustache
index b9927d11d677..174f82a303c5 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.cpp.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.cpp.mustache
@@ -22,7 +22,7 @@ void OauthBase::onFinish(QNetworkReply *rep)
     addToken(oauthToken(token, expiresIn, scope, type));
 }
 
-oauthToken OauthBase::getToken(QString scope)
+oauthToken OauthBase::getToken(const QString &scope)
 {
     auto tokenIt = m_oauthTokenMap.find(scope);
     return tokenIt != m_oauthTokenMap.end() ? tokenIt.value() : oauthToken();
@@ -35,7 +35,7 @@ void OauthBase::addToken(oauthToken token)
 
 }
 
-void OauthBase::removeToken(QString scope)
+void OauthBase::removeToken(const QString &scope)
 {
     m_oauthTokenMap.remove(scope);
 }
@@ -59,7 +59,7 @@ void OauthCode::unlink()
     disconnect(&m_server, nullptr, nullptr, nullptr);
 }
 
-void OauthCode::setVariables(QString authUrl, QString tokenUrl, QString scope, QString state, QString redirectUri, QString clientId, QString clientSecret, QString accessType){
+void OauthCode::setVariables(const QString &authUrl, const QString &tokenUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &clientSecret, const QString &accessType){
 
     m_authUrl = QUrl(authUrl);
     m_tokenUrl = QUrl(tokenUrl);
@@ -126,7 +126,7 @@ void OauthImplicit::unlink()
      m_linked = false;
 }
 
-void OauthImplicit::setVariables(QString authUrl, QString scope, QString state, QString redirectUri, QString clientId, QString accessType){
+void OauthImplicit::setVariables(const QString &authUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &accessType){
 
     m_authUrl = QUrl(authUrl);
     m_scope = scope;
@@ -168,7 +168,7 @@ void OauthCredentials::unlink()
     disconnect(this, nullptr, nullptr, nullptr);
 }
 
-void OauthCredentials::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret){
+void OauthCredentials::setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret){
 
     m_tokenUrl = QUrl(tokenUrl);
     m_scope = scope;
@@ -211,7 +211,7 @@ void OauthPassword::unlink()
     disconnect(this, nullptr, nullptr, nullptr);
 }
 
-void OauthPassword::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret, QString username, QString password){
+void OauthPassword::setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret, const QString &username, const QString &password){
 
     m_tokenUrl = QUrl(tokenUrl);
     m_scope = scope;
@@ -346,4 +346,4 @@ void ReplyServer::read()
 
 {{#cppNamespaceDeclarations}}
 } // namespace {{this}}
-{{/cppNamespaceDeclarations}}
\ No newline at end of file
+{{/cppNamespaceDeclarations}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.h.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.h.mustache
index dd5ca9474361..6e74e17e16af 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.h.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/oauth.h.mustache
@@ -53,7 +53,7 @@ class ReplyServer : public QTcpServer
     Q_OBJECT
 public:
     explicit ReplyServer(QObject *parent = nullptr);
-    void setReply(QByteArray reply){m_reply = reply;};
+    void setReply(const QByteArray &reply) {m_reply = reply;};
     void run();
 private:
     QByteArray m_reply;
@@ -74,9 +74,9 @@ class OauthBase : public QObject
     Q_OBJECT
 public: 
     OauthBase(QObject* parent = nullptr) : QObject(parent) {};
-    oauthToken getToken(QString scope);
+    oauthToken getToken(const QString &scope);
     void addToken(oauthToken token);
-    void removeToken(QString scope);
+    void removeToken(const QString &scope);
     bool linked(){return m_linked;};
     virtual void link()=0;
     virtual void unlink()=0;
@@ -105,7 +105,7 @@ public:
     OauthCode(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString authUrl, QString tokenUrl, QString scope, QString state, QString redirectUri, QString clientId, QString clientSecret, QString accessType = "");
+    void setVariables(const QString &authUrl, const QString &tokenUrl, const QString &scope, const QString  &state, const QString &redirectUri, const QString &clientId, const QString &clientSecret, const QString &accessType = QString());
 
 private:
     ReplyServer m_server;
@@ -124,7 +124,7 @@ public:
     OauthImplicit(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString authUrl, QString scope, QString state, QString redirectUri, QString clientId, QString accessType = "");
+    void setVariables(const QString &authUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &accessType = QString());
 
 private:
     ReplyServer m_server;
@@ -142,7 +142,7 @@ public:
     OauthCredentials(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret);
+    void setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret);
 
 public Q_SLOTS:
     void authenticationNeededCallback() override;
@@ -157,7 +157,7 @@ public:
     OauthPassword(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret, QString username, QString password);
+    void setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret, const QString &username, const QString &password);
 
 private:
     QString m_username, m_password;
diff --git a/modules/openapi-generator/src/main/resources/cpp-qt-client/object.mustache b/modules/openapi-generator/src/main/resources/cpp-qt-client/object.mustache
index 6a6b3758a867..7b6236801153 100644
--- a/modules/openapi-generator/src/main/resources/cpp-qt-client/object.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-qt-client/object.mustache
@@ -14,7 +14,7 @@ class {{prefix}}Object {
 public:
     {{prefix}}Object() {}
 
-    {{prefix}}Object(QString jsonString) {
+    {{prefix}}Object(const QString &jsonString) {
         fromJson(jsonString);
     }
 
@@ -29,7 +29,7 @@ public:
         return doc.toJson(QJsonDocument::Compact);
     }
 
-    virtual void fromJson(QString jsonString) {
+    virtual void fromJson(const QString &jsonString) {
         QJsonDocument doc = QJsonDocument::fromJson(jsonString.toUtf8());
         jObj = doc.object();
     }
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/README.md b/samples/client/petstore/cpp-qt-addDownloadProgress/README.md
index d1813e65b52d..50df38674c1f 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/README.md
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/README.md
@@ -63,7 +63,7 @@ void Example::exampleFunction1(){
       connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignal, [&]() {
           loop.quit();
       });
-      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, QString error_str) {
+      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, const QString &error_str) {
           qDebug() << "Error happened while issuing request : " << error_str;
           loop.quit();
       });
@@ -74,7 +74,7 @@ void Example::exampleFunction1(){
       connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignal, [&]() {
           loop.quit();
       });
-      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, QString error_str) {
+      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, const QString &error_str) {
           qDebug() << "Error happened while issuing request : " << error_str;
           loop.quit();
       });
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.cpp
index 8fbef0fb8c5c..ef7bb19bdb17 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXApiResponse::PFXApiResponse(QString json) {
+PFXApiResponse::PFXApiResponse(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -43,7 +43,7 @@ void PFXApiResponse::initializeModel() {
     m_message_isValid = false;
 }
 
-void PFXApiResponse::fromJson(QString jsonString) {
+void PFXApiResponse::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.h
index dc7682206561..fdf691fa6e59 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXApiResponse.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXApiResponse : public PFXObject {
 public:
     PFXApiResponse();
-    PFXApiResponse(QString json);
+    PFXApiResponse(const QString &json);
     ~PFXApiResponse() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint32 getCode() const;
     void setCode(const qint32 &code);
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.cpp
index 1651c44c1c35..46944b4aa07b 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXCategory::PFXCategory(QString json) {
+PFXCategory::PFXCategory(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -40,7 +40,7 @@ void PFXCategory::initializeModel() {
     m_name_isValid = false;
 }
 
-void PFXCategory::fromJson(QString jsonString) {
+void PFXCategory::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.h
index d86eee9a2626..9449837db442 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXCategory.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXCategory : public PFXObject {
 public:
     PFXCategory();
-    PFXCategory(QString json);
+    PFXCategory(const QString &json);
     ~PFXCategory() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnum.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnum.h
index 045cc6095c82..fa2a98482e7d 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnum.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnum.h
@@ -23,7 +23,7 @@ class PFXEnum {
 public:
     PFXEnum() {}
 
-    PFXEnum(QString jsonString) {
+    PFXEnum(const QString &jsonString) {
         fromJson(jsonString);
     }
 
@@ -43,7 +43,7 @@ class PFXEnum {
         return obj;
     }
 	
-    virtual void fromJson(QString jsonString) {
+    virtual void fromJson(const QString &jsonString) {
         jstr = jsonString;
     }
 
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.cpp
index da7f6d388a38..7c6f338e48c9 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXEnumStatus::PFXEnumStatus(QString json) {
+PFXEnumStatus::PFXEnumStatus(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -38,7 +38,7 @@ void PFXEnumStatus::initializeModel() {
     m_value = ePFXEnumStatus::INVALID_VALUE_OPENAPI_GENERATED;
 }
 
-void PFXEnumStatus::fromJson(QString jsonString) {
+void PFXEnumStatus::fromJson(const QString &jsonString) {
     
     if ( jsonString.compare("placed", Qt::CaseInsensitive) == 0) {
         m_value = ePFXEnumStatus::PLACED;
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.h
index 10d787b9e4d9..fa19717e1340 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXEnumStatus.h
@@ -29,13 +29,13 @@ namespace test_namespace {
 class PFXEnumStatus : public PFXEnum {
 public:
     PFXEnumStatus();
-    PFXEnumStatus(QString json);
+    PFXEnumStatus(const QString &json);
     ~PFXEnumStatus() override;
 
     QString asJson() const override;
     QJsonValue asJsonValue() const override;
     void fromJsonValue(QJsonValue json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     enum class ePFXEnumStatus {
         INVALID_VALUE_OPENAPI_GENERATED = 0,
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.cpp
index de3615747bd6..00b953e89b2f 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.cpp
@@ -17,6 +17,9 @@
 #include <QUrl>
 #include <QUuid>
 #include <QtGlobal>
+#include <QtAlgorithms>
+
+#include <utility>
 
 
 #include "PFXHttpRequest.h"
@@ -27,7 +30,7 @@ PFXHttpRequestInput::PFXHttpRequestInput() {
     initialize();
 }
 
-PFXHttpRequestInput::PFXHttpRequestInput(QString v_url_str, QString v_http_method) {
+PFXHttpRequestInput::PFXHttpRequestInput(const QString &v_url_str, const QString &v_http_method) {
     initialize();
     url_str = v_url_str;
     http_method = v_http_method;
@@ -39,11 +42,11 @@ void PFXHttpRequestInput::initialize() {
     http_method = "GET";
 }
 
-void PFXHttpRequestInput::add_var(QString key, QString value) {
+void PFXHttpRequestInput::add_var(const QString &key, const QString &value) {
     vars[key] = value;
 }
 
-void PFXHttpRequestInput::add_file(QString variable_name, QString local_filename, QString request_filename, QString mime_type) {
+void PFXHttpRequestInput::add_file(const QString &variable_name, const QString &local_filename, const QString &request_filename, const QString &mime_type) {
     PFXHttpFileElement file;
     file.variable_name = variable_name;
     file.local_filename = local_filename;
@@ -65,11 +68,7 @@ PFXHttpRequestWorker::PFXHttpRequestWorker(QObject *parent, QNetworkAccessManage
 PFXHttpRequestWorker::~PFXHttpRequestWorker() {
     QObject::disconnect(&timeOutTimer, &QTimer::timeout, nullptr, nullptr);
     timeOutTimer.stop();
-    for (const auto &item : multiPartFields) {
-        if (item != nullptr) {
-            delete item;
-        }
-    }
+    qDeleteAll(multiPartFields);
 }
 
 QMap<QString, QString> PFXHttpRequestWorker::getResponseHeaders() const {
@@ -123,10 +122,10 @@ int  PFXHttpRequestWorker::getHttpResponseCode() const{
     return httpResponseCode;
 }
 
-QString PFXHttpRequestWorker::http_attribute_encode(QString attribute_name, QString input) {
+QString PFXHttpRequestWorker::http_attribute_encode(const QString &attribute_name, const QString &input) {
     // result structure follows RFC 5987
     bool need_utf_encoding = false;
-    QString result = "";
+    QString result;
     QByteArray input_c = input.toLocal8Bit();
     char c;
     for (int i = 0; i < input_c.length(); i++) {
@@ -150,7 +149,7 @@ QString PFXHttpRequestWorker::http_attribute_encode(QString attribute_name, QStr
         return QString("%1=\"%2\"").arg(attribute_name, result);
     }
 
-    QString result_utf8 = "";
+    QString result_utf8;
     for (int i = 0; i < input_c.length(); i++) {
         c = input_c.at(i);
         if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
@@ -185,7 +184,7 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
 
     // prepare request content
 
-    QString boundary = "";
+    QString boundary;
 
     if (input->var_layout == ADDRESS || input->var_layout == URL_ENCODED) {
         // variable layout is ADDRESS or URL_ENCODED
@@ -193,7 +192,7 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
         if (input->vars.count() > 0) {
             bool first = true;
             isFormData = true;
-            for (QString key : input->vars.keys()) {
+            for (const QString &key : input->vars.keys()) {
                 if (!first) {
                     request_content.append("&");
                 }
@@ -215,11 +214,11 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
         boundary = QString("__-----------------------%1%2")
                             .arg(QDateTime::currentSecsSinceEpoch())
                             .arg(randomGenerator.generate());
-        QString boundary_delimiter = "--";
-        QString new_line = "\r\n";
+        const QString boundary_delimiter = "--";
+        const QString new_line = "\r\n";
 
         // add variables
-        for (QString key : input->vars.keys()) {
+        for (const QString &key : input->vars.keys()) {
             // add boundary
             request_content.append(boundary_delimiter.toUtf8());
             request_content.append(boundary.toUtf8());
@@ -321,7 +320,7 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
         request.setSslConfiguration(*PFXHttpRequestWorker::sslDefaultConfiguration);
     }
     request.setRawHeader("User-Agent", "OpenAPI-Generator/1.0.0/cpp-qt");
-    for (QString key : input->headers.keys()) { request.setRawHeader(key.toStdString().c_str(), input->headers.value(key).toStdString().c_str()); }
+    for (const QString &key : input->headers.keys()) { request.setRawHeader(key.toStdString().c_str(), input->headers.value(key).toStdString().c_str()); }
 
     if (request_content.size() > 0 && !isFormData && (input->var_layout != MULTIPART)) {
         if (!input->headers.contains("Content-Type")) {
@@ -411,7 +410,7 @@ void PFXHttpRequestWorker::process_response(QNetworkReply *reply) {
     QString contentTypeHdr;
     QString contentEncodingHdr;
 
-    for(auto hdr: getResponseHeaders().keys()){
+    for(const auto &hdr: getResponseHeaders().keys()){
         if(hdr.compare(QString("Content-Disposition"), Qt::CaseInsensitive) == 0){
             contentDispositionHdr = getResponseHeaders().value(hdr);
         }
@@ -429,7 +428,7 @@ void PFXHttpRequestWorker::process_response(QNetworkReply *reply) {
             !contentTypeHdr.isEmpty() ? contentTypeHdr.split(QString(";"), Qt::SkipEmptyParts).first() : QString();
         if ((contentDisposition.count() > 0) && (contentDisposition.first() == QString("attachment"))) {
             QString filename = QUuid::createUuid().toString();
-            for (const auto &file : contentDisposition) {
+            for (const auto &file : std::as_const(contentDisposition)) {
                 if (file.contains(QString("filename"))) {
                     filename = file.split(QString("="), Qt::SkipEmptyParts).at(1);
                     break;
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.h
index 3ebd6e1724a1..138f9e13a38c 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXHttpRequest.h
@@ -49,10 +49,10 @@ class PFXHttpRequestInput {
     QByteArray request_body;
 
     PFXHttpRequestInput();
-    PFXHttpRequestInput(QString v_url_str, QString v_http_method);
+    PFXHttpRequestInput(const QString &v_url_str, const QString &v_http_method);
     void initialize();
-    void add_var(QString key, QString value);
-    void add_file(QString variable_name, QString local_filename, QString request_filename, QString mime_type);
+    void add_var(const QString &key, const QString &value);
+    void add_file(const QString &variable_name, const QString &local_filename, const QString &request_filename, const QString &mime_type);
 };
 
 class PFXHttpRequestWorker : public QObject {
@@ -67,7 +67,7 @@ class PFXHttpRequestWorker : public QObject {
     QString error_str;
 
     QMap<QString, QString> getResponseHeaders() const;
-    QString http_attribute_encode(QString attribute_name, QString input);
+    QString http_attribute_encode(const QString &attribute_name, const QString &input);
     void execute(PFXHttpRequestInput *input);
     static QSslConfiguration *sslDefaultConfiguration;
     void setTimeOut(int timeOutMs);
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.cpp
index c22d3a849997..3024053e10d7 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.cpp
@@ -20,7 +20,7 @@ void OauthBase::onFinish(QNetworkReply *rep)
     addToken(oauthToken(token, expiresIn, scope, type));
 }
 
-oauthToken OauthBase::getToken(QString scope)
+oauthToken OauthBase::getToken(const QString &scope)
 {
     auto tokenIt = m_oauthTokenMap.find(scope);
     return tokenIt != m_oauthTokenMap.end() ? tokenIt.value() : oauthToken();
@@ -33,7 +33,7 @@ void OauthBase::addToken(oauthToken token)
 
 }
 
-void OauthBase::removeToken(QString scope)
+void OauthBase::removeToken(const QString &scope)
 {
     m_oauthTokenMap.remove(scope);
 }
@@ -57,7 +57,7 @@ void OauthCode::unlink()
     disconnect(&m_server, nullptr, nullptr, nullptr);
 }
 
-void OauthCode::setVariables(QString authUrl, QString tokenUrl, QString scope, QString state, QString redirectUri, QString clientId, QString clientSecret, QString accessType){
+void OauthCode::setVariables(const QString &authUrl, const QString &tokenUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &clientSecret, const QString &accessType){
 
     m_authUrl = QUrl(authUrl);
     m_tokenUrl = QUrl(tokenUrl);
@@ -124,7 +124,7 @@ void OauthImplicit::unlink()
      m_linked = false;
 }
 
-void OauthImplicit::setVariables(QString authUrl, QString scope, QString state, QString redirectUri, QString clientId, QString accessType){
+void OauthImplicit::setVariables(const QString &authUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &accessType){
 
     m_authUrl = QUrl(authUrl);
     m_scope = scope;
@@ -166,7 +166,7 @@ void OauthCredentials::unlink()
     disconnect(this, nullptr, nullptr, nullptr);
 }
 
-void OauthCredentials::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret){
+void OauthCredentials::setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret){
 
     m_tokenUrl = QUrl(tokenUrl);
     m_scope = scope;
@@ -209,7 +209,7 @@ void OauthPassword::unlink()
     disconnect(this, nullptr, nullptr, nullptr);
 }
 
-void OauthPassword::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret, QString username, QString password){
+void OauthPassword::setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret, const QString &username, const QString &password){
 
     m_tokenUrl = QUrl(tokenUrl);
     m_scope = scope;
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.h
index 9038d05940c2..471862af1a7d 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOauth.h
@@ -61,7 +61,7 @@ class ReplyServer : public QTcpServer
     Q_OBJECT
 public:
     explicit ReplyServer(QObject *parent = nullptr);
-    void setReply(QByteArray reply){m_reply = reply;};
+    void setReply(const QByteArray &reply) {m_reply = reply;};
     void run();
 private:
     QByteArray m_reply;
@@ -82,9 +82,9 @@ class OauthBase : public QObject
     Q_OBJECT
 public: 
     OauthBase(QObject* parent = nullptr) : QObject(parent) {};
-    oauthToken getToken(QString scope);
+    oauthToken getToken(const QString &scope);
     void addToken(oauthToken token);
-    void removeToken(QString scope);
+    void removeToken(const QString &scope);
     bool linked(){return m_linked;};
     virtual void link()=0;
     virtual void unlink()=0;
@@ -113,7 +113,7 @@ class OauthCode : public OauthBase
     OauthCode(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString authUrl, QString tokenUrl, QString scope, QString state, QString redirectUri, QString clientId, QString clientSecret, QString accessType = "");
+    void setVariables(const QString &authUrl, const QString &tokenUrl, const QString &scope, const QString  &state, const QString &redirectUri, const QString &clientId, const QString &clientSecret, const QString &accessType = QString());
 
 private:
     ReplyServer m_server;
@@ -132,7 +132,7 @@ class OauthImplicit : public OauthBase
     OauthImplicit(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString authUrl, QString scope, QString state, QString redirectUri, QString clientId, QString accessType = "");
+    void setVariables(const QString &authUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &accessType = QString());
 
 private:
     ReplyServer m_server;
@@ -150,7 +150,7 @@ class OauthCredentials : public OauthBase
     OauthCredentials(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret);
+    void setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret);
 
 public Q_SLOTS:
     void authenticationNeededCallback() override;
@@ -165,7 +165,7 @@ class OauthPassword : public OauthBase
     OauthPassword(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret, QString username, QString password);
+    void setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret, const QString &username, const QString &password);
 
 private:
     QString m_username, m_password;
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXObject.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXObject.h
index 7b2e81b53440..9bdd1e8c5439 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXObject.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXObject.h
@@ -22,7 +22,7 @@ class PFXObject {
 public:
     PFXObject() {}
 
-    PFXObject(QString jsonString) {
+    PFXObject(const QString &jsonString) {
         fromJson(jsonString);
     }
 
@@ -37,7 +37,7 @@ class PFXObject {
         return doc.toJson(QJsonDocument::Compact);
     }
 
-    virtual void fromJson(QString jsonString) {
+    virtual void fromJson(const QString &jsonString) {
         QJsonDocument doc = QJsonDocument::fromJson(jsonString.toUtf8());
         jObj = doc.object();
     }
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.cpp
index 15f7e8c36011..bb299fd96336 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXOrder::PFXOrder(QString json) {
+PFXOrder::PFXOrder(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -52,7 +52,7 @@ void PFXOrder::initializeModel() {
     m_complete_isValid = false;
 }
 
-void PFXOrder::fromJson(QString jsonString) {
+void PFXOrder::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.h
index 3d58afa70e30..eb1ff9c9d223 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXOrder.h
@@ -31,13 +31,13 @@ namespace test_namespace {
 class PFXOrder : public PFXObject {
 public:
     PFXOrder();
-    PFXOrder(QString json);
+    PFXOrder(const QString &json);
     ~PFXOrder() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.cpp
index 6f99209ba90a..dc9d4d036940 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXPet::PFXPet(QString json) {
+PFXPet::PFXPet(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -52,7 +52,7 @@ void PFXPet::initializeModel() {
     m_status_isValid = false;
 }
 
-void PFXPet::fromJson(QString jsonString) {
+void PFXPet::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.h
index 86395d417ac2..3cf5dd9a4e6b 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXPet.h
@@ -35,13 +35,13 @@ class PFXTag;
 class PFXPet : public PFXObject {
 public:
     PFXPet();
-    PFXPet(QString json);
+    PFXPet(const QString &json);
     ~PFXPet() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.cpp
index ea32dc814765..255653d5f7a0 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXTag::PFXTag(QString json) {
+PFXTag::PFXTag(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -40,7 +40,7 @@ void PFXTag::initializeModel() {
     m_name_isValid = false;
 }
 
-void PFXTag::fromJson(QString jsonString) {
+void PFXTag::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.h
index 808aab4519e0..5cb5196bfad7 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTag.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXTag : public PFXObject {
 public:
     PFXTag();
-    PFXTag(QString json);
+    PFXTag(const QString &json);
     ~PFXTag() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.cpp
index f0baa2c149e5..d5ef6d36da48 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXTestAnyType::PFXTestAnyType(QString json) {
+PFXTestAnyType::PFXTestAnyType(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -40,7 +40,7 @@ void PFXTestAnyType::initializeModel() {
     m_message_isValid = false;
 }
 
-void PFXTestAnyType::fromJson(QString jsonString) {
+void PFXTestAnyType::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.h
index b8a76d1fc964..49228ad295e2 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXTestAnyType.h
@@ -31,13 +31,13 @@ namespace test_namespace {
 class PFXTestAnyType : public PFXObject {
 public:
     PFXTestAnyType();
-    PFXTestAnyType(QString json);
+    PFXTestAnyType(const QString &json);
     ~PFXTestAnyType() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     QJsonValue getCode() const;
     void setCode(const QJsonValue &code);
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.cpp b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.cpp
index e466a42424cc..c329701733b4 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.cpp
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXUser::PFXUser(QString json) {
+PFXUser::PFXUser(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -58,7 +58,7 @@ void PFXUser::initializeModel() {
     m_user_status_isValid = false;
 }
 
-void PFXUser::fromJson(QString jsonString) {
+void PFXUser::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.h b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.h
index 5a3def81b532..509dd5420cd5 100644
--- a/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.h
+++ b/samples/client/petstore/cpp-qt-addDownloadProgress/client/PFXUser.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXUser : public PFXObject {
 public:
     PFXUser();
-    PFXUser(QString json);
+    PFXUser(const QString &json);
     ~PFXUser() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt/README.md b/samples/client/petstore/cpp-qt/README.md
index d1813e65b52d..50df38674c1f 100644
--- a/samples/client/petstore/cpp-qt/README.md
+++ b/samples/client/petstore/cpp-qt/README.md
@@ -63,7 +63,7 @@ void Example::exampleFunction1(){
       connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignal, [&]() {
           loop.quit();
       });
-      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, QString error_str) {
+      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, const QString &error_str) {
           qDebug() << "Error happened while issuing request : " << error_str;
           loop.quit();
       });
@@ -74,7 +74,7 @@ void Example::exampleFunction1(){
       connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignal, [&]() {
           loop.quit();
       });
-      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, QString error_str) {
+      connect(&apiInstance, &PFXFakeApi::getEnumInlineOrRefSignalE, [&](QNetworkReply::NetworkError, const QString &error_str) {
           qDebug() << "Error happened while issuing request : " << error_str;
           loop.quit();
       });
diff --git a/samples/client/petstore/cpp-qt/client/PFXApiResponse.cpp b/samples/client/petstore/cpp-qt/client/PFXApiResponse.cpp
index 8fbef0fb8c5c..ef7bb19bdb17 100644
--- a/samples/client/petstore/cpp-qt/client/PFXApiResponse.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXApiResponse.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXApiResponse::PFXApiResponse(QString json) {
+PFXApiResponse::PFXApiResponse(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -43,7 +43,7 @@ void PFXApiResponse::initializeModel() {
     m_message_isValid = false;
 }
 
-void PFXApiResponse::fromJson(QString jsonString) {
+void PFXApiResponse::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt/client/PFXApiResponse.h b/samples/client/petstore/cpp-qt/client/PFXApiResponse.h
index dc7682206561..fdf691fa6e59 100644
--- a/samples/client/petstore/cpp-qt/client/PFXApiResponse.h
+++ b/samples/client/petstore/cpp-qt/client/PFXApiResponse.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXApiResponse : public PFXObject {
 public:
     PFXApiResponse();
-    PFXApiResponse(QString json);
+    PFXApiResponse(const QString &json);
     ~PFXApiResponse() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint32 getCode() const;
     void setCode(const qint32 &code);
diff --git a/samples/client/petstore/cpp-qt/client/PFXCategory.cpp b/samples/client/petstore/cpp-qt/client/PFXCategory.cpp
index 1651c44c1c35..46944b4aa07b 100644
--- a/samples/client/petstore/cpp-qt/client/PFXCategory.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXCategory.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXCategory::PFXCategory(QString json) {
+PFXCategory::PFXCategory(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -40,7 +40,7 @@ void PFXCategory::initializeModel() {
     m_name_isValid = false;
 }
 
-void PFXCategory::fromJson(QString jsonString) {
+void PFXCategory::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt/client/PFXCategory.h b/samples/client/petstore/cpp-qt/client/PFXCategory.h
index d86eee9a2626..9449837db442 100644
--- a/samples/client/petstore/cpp-qt/client/PFXCategory.h
+++ b/samples/client/petstore/cpp-qt/client/PFXCategory.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXCategory : public PFXObject {
 public:
     PFXCategory();
-    PFXCategory(QString json);
+    PFXCategory(const QString &json);
     ~PFXCategory() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt/client/PFXEnum.h b/samples/client/petstore/cpp-qt/client/PFXEnum.h
index 045cc6095c82..fa2a98482e7d 100644
--- a/samples/client/petstore/cpp-qt/client/PFXEnum.h
+++ b/samples/client/petstore/cpp-qt/client/PFXEnum.h
@@ -23,7 +23,7 @@ class PFXEnum {
 public:
     PFXEnum() {}
 
-    PFXEnum(QString jsonString) {
+    PFXEnum(const QString &jsonString) {
         fromJson(jsonString);
     }
 
@@ -43,7 +43,7 @@ class PFXEnum {
         return obj;
     }
 	
-    virtual void fromJson(QString jsonString) {
+    virtual void fromJson(const QString &jsonString) {
         jstr = jsonString;
     }
 
diff --git a/samples/client/petstore/cpp-qt/client/PFXEnumStatus.cpp b/samples/client/petstore/cpp-qt/client/PFXEnumStatus.cpp
index da7f6d388a38..7c6f338e48c9 100644
--- a/samples/client/petstore/cpp-qt/client/PFXEnumStatus.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXEnumStatus.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXEnumStatus::PFXEnumStatus(QString json) {
+PFXEnumStatus::PFXEnumStatus(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -38,7 +38,7 @@ void PFXEnumStatus::initializeModel() {
     m_value = ePFXEnumStatus::INVALID_VALUE_OPENAPI_GENERATED;
 }
 
-void PFXEnumStatus::fromJson(QString jsonString) {
+void PFXEnumStatus::fromJson(const QString &jsonString) {
     
     if ( jsonString.compare("placed", Qt::CaseInsensitive) == 0) {
         m_value = ePFXEnumStatus::PLACED;
diff --git a/samples/client/petstore/cpp-qt/client/PFXEnumStatus.h b/samples/client/petstore/cpp-qt/client/PFXEnumStatus.h
index 10d787b9e4d9..fa19717e1340 100644
--- a/samples/client/petstore/cpp-qt/client/PFXEnumStatus.h
+++ b/samples/client/petstore/cpp-qt/client/PFXEnumStatus.h
@@ -29,13 +29,13 @@ namespace test_namespace {
 class PFXEnumStatus : public PFXEnum {
 public:
     PFXEnumStatus();
-    PFXEnumStatus(QString json);
+    PFXEnumStatus(const QString &json);
     ~PFXEnumStatus() override;
 
     QString asJson() const override;
     QJsonValue asJsonValue() const override;
     void fromJsonValue(QJsonValue json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     enum class ePFXEnumStatus {
         INVALID_VALUE_OPENAPI_GENERATED = 0,
diff --git a/samples/client/petstore/cpp-qt/client/PFXHttpRequest.cpp b/samples/client/petstore/cpp-qt/client/PFXHttpRequest.cpp
index de3615747bd6..00b953e89b2f 100644
--- a/samples/client/petstore/cpp-qt/client/PFXHttpRequest.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXHttpRequest.cpp
@@ -17,6 +17,9 @@
 #include <QUrl>
 #include <QUuid>
 #include <QtGlobal>
+#include <QtAlgorithms>
+
+#include <utility>
 
 
 #include "PFXHttpRequest.h"
@@ -27,7 +30,7 @@ PFXHttpRequestInput::PFXHttpRequestInput() {
     initialize();
 }
 
-PFXHttpRequestInput::PFXHttpRequestInput(QString v_url_str, QString v_http_method) {
+PFXHttpRequestInput::PFXHttpRequestInput(const QString &v_url_str, const QString &v_http_method) {
     initialize();
     url_str = v_url_str;
     http_method = v_http_method;
@@ -39,11 +42,11 @@ void PFXHttpRequestInput::initialize() {
     http_method = "GET";
 }
 
-void PFXHttpRequestInput::add_var(QString key, QString value) {
+void PFXHttpRequestInput::add_var(const QString &key, const QString &value) {
     vars[key] = value;
 }
 
-void PFXHttpRequestInput::add_file(QString variable_name, QString local_filename, QString request_filename, QString mime_type) {
+void PFXHttpRequestInput::add_file(const QString &variable_name, const QString &local_filename, const QString &request_filename, const QString &mime_type) {
     PFXHttpFileElement file;
     file.variable_name = variable_name;
     file.local_filename = local_filename;
@@ -65,11 +68,7 @@ PFXHttpRequestWorker::PFXHttpRequestWorker(QObject *parent, QNetworkAccessManage
 PFXHttpRequestWorker::~PFXHttpRequestWorker() {
     QObject::disconnect(&timeOutTimer, &QTimer::timeout, nullptr, nullptr);
     timeOutTimer.stop();
-    for (const auto &item : multiPartFields) {
-        if (item != nullptr) {
-            delete item;
-        }
-    }
+    qDeleteAll(multiPartFields);
 }
 
 QMap<QString, QString> PFXHttpRequestWorker::getResponseHeaders() const {
@@ -123,10 +122,10 @@ int  PFXHttpRequestWorker::getHttpResponseCode() const{
     return httpResponseCode;
 }
 
-QString PFXHttpRequestWorker::http_attribute_encode(QString attribute_name, QString input) {
+QString PFXHttpRequestWorker::http_attribute_encode(const QString &attribute_name, const QString &input) {
     // result structure follows RFC 5987
     bool need_utf_encoding = false;
-    QString result = "";
+    QString result;
     QByteArray input_c = input.toLocal8Bit();
     char c;
     for (int i = 0; i < input_c.length(); i++) {
@@ -150,7 +149,7 @@ QString PFXHttpRequestWorker::http_attribute_encode(QString attribute_name, QStr
         return QString("%1=\"%2\"").arg(attribute_name, result);
     }
 
-    QString result_utf8 = "";
+    QString result_utf8;
     for (int i = 0; i < input_c.length(); i++) {
         c = input_c.at(i);
         if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
@@ -185,7 +184,7 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
 
     // prepare request content
 
-    QString boundary = "";
+    QString boundary;
 
     if (input->var_layout == ADDRESS || input->var_layout == URL_ENCODED) {
         // variable layout is ADDRESS or URL_ENCODED
@@ -193,7 +192,7 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
         if (input->vars.count() > 0) {
             bool first = true;
             isFormData = true;
-            for (QString key : input->vars.keys()) {
+            for (const QString &key : input->vars.keys()) {
                 if (!first) {
                     request_content.append("&");
                 }
@@ -215,11 +214,11 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
         boundary = QString("__-----------------------%1%2")
                             .arg(QDateTime::currentSecsSinceEpoch())
                             .arg(randomGenerator.generate());
-        QString boundary_delimiter = "--";
-        QString new_line = "\r\n";
+        const QString boundary_delimiter = "--";
+        const QString new_line = "\r\n";
 
         // add variables
-        for (QString key : input->vars.keys()) {
+        for (const QString &key : input->vars.keys()) {
             // add boundary
             request_content.append(boundary_delimiter.toUtf8());
             request_content.append(boundary.toUtf8());
@@ -321,7 +320,7 @@ void PFXHttpRequestWorker::execute(PFXHttpRequestInput *input) {
         request.setSslConfiguration(*PFXHttpRequestWorker::sslDefaultConfiguration);
     }
     request.setRawHeader("User-Agent", "OpenAPI-Generator/1.0.0/cpp-qt");
-    for (QString key : input->headers.keys()) { request.setRawHeader(key.toStdString().c_str(), input->headers.value(key).toStdString().c_str()); }
+    for (const QString &key : input->headers.keys()) { request.setRawHeader(key.toStdString().c_str(), input->headers.value(key).toStdString().c_str()); }
 
     if (request_content.size() > 0 && !isFormData && (input->var_layout != MULTIPART)) {
         if (!input->headers.contains("Content-Type")) {
@@ -411,7 +410,7 @@ void PFXHttpRequestWorker::process_response(QNetworkReply *reply) {
     QString contentTypeHdr;
     QString contentEncodingHdr;
 
-    for(auto hdr: getResponseHeaders().keys()){
+    for(const auto &hdr: getResponseHeaders().keys()){
         if(hdr.compare(QString("Content-Disposition"), Qt::CaseInsensitive) == 0){
             contentDispositionHdr = getResponseHeaders().value(hdr);
         }
@@ -429,7 +428,7 @@ void PFXHttpRequestWorker::process_response(QNetworkReply *reply) {
             !contentTypeHdr.isEmpty() ? contentTypeHdr.split(QString(";"), Qt::SkipEmptyParts).first() : QString();
         if ((contentDisposition.count() > 0) && (contentDisposition.first() == QString("attachment"))) {
             QString filename = QUuid::createUuid().toString();
-            for (const auto &file : contentDisposition) {
+            for (const auto &file : std::as_const(contentDisposition)) {
                 if (file.contains(QString("filename"))) {
                     filename = file.split(QString("="), Qt::SkipEmptyParts).at(1);
                     break;
diff --git a/samples/client/petstore/cpp-qt/client/PFXHttpRequest.h b/samples/client/petstore/cpp-qt/client/PFXHttpRequest.h
index 3ebd6e1724a1..138f9e13a38c 100644
--- a/samples/client/petstore/cpp-qt/client/PFXHttpRequest.h
+++ b/samples/client/petstore/cpp-qt/client/PFXHttpRequest.h
@@ -49,10 +49,10 @@ class PFXHttpRequestInput {
     QByteArray request_body;
 
     PFXHttpRequestInput();
-    PFXHttpRequestInput(QString v_url_str, QString v_http_method);
+    PFXHttpRequestInput(const QString &v_url_str, const QString &v_http_method);
     void initialize();
-    void add_var(QString key, QString value);
-    void add_file(QString variable_name, QString local_filename, QString request_filename, QString mime_type);
+    void add_var(const QString &key, const QString &value);
+    void add_file(const QString &variable_name, const QString &local_filename, const QString &request_filename, const QString &mime_type);
 };
 
 class PFXHttpRequestWorker : public QObject {
@@ -67,7 +67,7 @@ class PFXHttpRequestWorker : public QObject {
     QString error_str;
 
     QMap<QString, QString> getResponseHeaders() const;
-    QString http_attribute_encode(QString attribute_name, QString input);
+    QString http_attribute_encode(const QString &attribute_name, const QString &input);
     void execute(PFXHttpRequestInput *input);
     static QSslConfiguration *sslDefaultConfiguration;
     void setTimeOut(int timeOutMs);
diff --git a/samples/client/petstore/cpp-qt/client/PFXOauth.cpp b/samples/client/petstore/cpp-qt/client/PFXOauth.cpp
index c22d3a849997..3024053e10d7 100644
--- a/samples/client/petstore/cpp-qt/client/PFXOauth.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXOauth.cpp
@@ -20,7 +20,7 @@ void OauthBase::onFinish(QNetworkReply *rep)
     addToken(oauthToken(token, expiresIn, scope, type));
 }
 
-oauthToken OauthBase::getToken(QString scope)
+oauthToken OauthBase::getToken(const QString &scope)
 {
     auto tokenIt = m_oauthTokenMap.find(scope);
     return tokenIt != m_oauthTokenMap.end() ? tokenIt.value() : oauthToken();
@@ -33,7 +33,7 @@ void OauthBase::addToken(oauthToken token)
 
 }
 
-void OauthBase::removeToken(QString scope)
+void OauthBase::removeToken(const QString &scope)
 {
     m_oauthTokenMap.remove(scope);
 }
@@ -57,7 +57,7 @@ void OauthCode::unlink()
     disconnect(&m_server, nullptr, nullptr, nullptr);
 }
 
-void OauthCode::setVariables(QString authUrl, QString tokenUrl, QString scope, QString state, QString redirectUri, QString clientId, QString clientSecret, QString accessType){
+void OauthCode::setVariables(const QString &authUrl, const QString &tokenUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &clientSecret, const QString &accessType){
 
     m_authUrl = QUrl(authUrl);
     m_tokenUrl = QUrl(tokenUrl);
@@ -124,7 +124,7 @@ void OauthImplicit::unlink()
      m_linked = false;
 }
 
-void OauthImplicit::setVariables(QString authUrl, QString scope, QString state, QString redirectUri, QString clientId, QString accessType){
+void OauthImplicit::setVariables(const QString &authUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &accessType){
 
     m_authUrl = QUrl(authUrl);
     m_scope = scope;
@@ -166,7 +166,7 @@ void OauthCredentials::unlink()
     disconnect(this, nullptr, nullptr, nullptr);
 }
 
-void OauthCredentials::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret){
+void OauthCredentials::setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret){
 
     m_tokenUrl = QUrl(tokenUrl);
     m_scope = scope;
@@ -209,7 +209,7 @@ void OauthPassword::unlink()
     disconnect(this, nullptr, nullptr, nullptr);
 }
 
-void OauthPassword::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret, QString username, QString password){
+void OauthPassword::setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret, const QString &username, const QString &password){
 
     m_tokenUrl = QUrl(tokenUrl);
     m_scope = scope;
diff --git a/samples/client/petstore/cpp-qt/client/PFXOauth.h b/samples/client/petstore/cpp-qt/client/PFXOauth.h
index 9038d05940c2..471862af1a7d 100644
--- a/samples/client/petstore/cpp-qt/client/PFXOauth.h
+++ b/samples/client/petstore/cpp-qt/client/PFXOauth.h
@@ -61,7 +61,7 @@ class ReplyServer : public QTcpServer
     Q_OBJECT
 public:
     explicit ReplyServer(QObject *parent = nullptr);
-    void setReply(QByteArray reply){m_reply = reply;};
+    void setReply(const QByteArray &reply) {m_reply = reply;};
     void run();
 private:
     QByteArray m_reply;
@@ -82,9 +82,9 @@ class OauthBase : public QObject
     Q_OBJECT
 public: 
     OauthBase(QObject* parent = nullptr) : QObject(parent) {};
-    oauthToken getToken(QString scope);
+    oauthToken getToken(const QString &scope);
     void addToken(oauthToken token);
-    void removeToken(QString scope);
+    void removeToken(const QString &scope);
     bool linked(){return m_linked;};
     virtual void link()=0;
     virtual void unlink()=0;
@@ -113,7 +113,7 @@ class OauthCode : public OauthBase
     OauthCode(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString authUrl, QString tokenUrl, QString scope, QString state, QString redirectUri, QString clientId, QString clientSecret, QString accessType = "");
+    void setVariables(const QString &authUrl, const QString &tokenUrl, const QString &scope, const QString  &state, const QString &redirectUri, const QString &clientId, const QString &clientSecret, const QString &accessType = QString());
 
 private:
     ReplyServer m_server;
@@ -132,7 +132,7 @@ class OauthImplicit : public OauthBase
     OauthImplicit(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString authUrl, QString scope, QString state, QString redirectUri, QString clientId, QString accessType = "");
+    void setVariables(const QString &authUrl, const QString &scope, const QString &state, const QString &redirectUri, const QString &clientId, const QString &accessType = QString());
 
 private:
     ReplyServer m_server;
@@ -150,7 +150,7 @@ class OauthCredentials : public OauthBase
     OauthCredentials(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret);
+    void setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret);
 
 public Q_SLOTS:
     void authenticationNeededCallback() override;
@@ -165,7 +165,7 @@ class OauthPassword : public OauthBase
     OauthPassword(QObject *parent = nullptr);
     void link() override;
     void unlink() override;
-    void setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret, QString username, QString password);
+    void setVariables(const QString &tokenUrl, const QString &scope, const QString &clientId, const QString &clientSecret, const QString &username, const QString &password);
 
 private:
     QString m_username, m_password;
diff --git a/samples/client/petstore/cpp-qt/client/PFXObject.h b/samples/client/petstore/cpp-qt/client/PFXObject.h
index 7b2e81b53440..9bdd1e8c5439 100644
--- a/samples/client/petstore/cpp-qt/client/PFXObject.h
+++ b/samples/client/petstore/cpp-qt/client/PFXObject.h
@@ -22,7 +22,7 @@ class PFXObject {
 public:
     PFXObject() {}
 
-    PFXObject(QString jsonString) {
+    PFXObject(const QString &jsonString) {
         fromJson(jsonString);
     }
 
@@ -37,7 +37,7 @@ class PFXObject {
         return doc.toJson(QJsonDocument::Compact);
     }
 
-    virtual void fromJson(QString jsonString) {
+    virtual void fromJson(const QString &jsonString) {
         QJsonDocument doc = QJsonDocument::fromJson(jsonString.toUtf8());
         jObj = doc.object();
     }
diff --git a/samples/client/petstore/cpp-qt/client/PFXOrder.cpp b/samples/client/petstore/cpp-qt/client/PFXOrder.cpp
index 15f7e8c36011..bb299fd96336 100644
--- a/samples/client/petstore/cpp-qt/client/PFXOrder.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXOrder.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXOrder::PFXOrder(QString json) {
+PFXOrder::PFXOrder(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -52,7 +52,7 @@ void PFXOrder::initializeModel() {
     m_complete_isValid = false;
 }
 
-void PFXOrder::fromJson(QString jsonString) {
+void PFXOrder::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt/client/PFXOrder.h b/samples/client/petstore/cpp-qt/client/PFXOrder.h
index 3d58afa70e30..eb1ff9c9d223 100644
--- a/samples/client/petstore/cpp-qt/client/PFXOrder.h
+++ b/samples/client/petstore/cpp-qt/client/PFXOrder.h
@@ -31,13 +31,13 @@ namespace test_namespace {
 class PFXOrder : public PFXObject {
 public:
     PFXOrder();
-    PFXOrder(QString json);
+    PFXOrder(const QString &json);
     ~PFXOrder() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt/client/PFXPet.cpp b/samples/client/petstore/cpp-qt/client/PFXPet.cpp
index 6f99209ba90a..dc9d4d036940 100644
--- a/samples/client/petstore/cpp-qt/client/PFXPet.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXPet.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXPet::PFXPet(QString json) {
+PFXPet::PFXPet(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -52,7 +52,7 @@ void PFXPet::initializeModel() {
     m_status_isValid = false;
 }
 
-void PFXPet::fromJson(QString jsonString) {
+void PFXPet::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt/client/PFXPet.h b/samples/client/petstore/cpp-qt/client/PFXPet.h
index 86395d417ac2..3cf5dd9a4e6b 100644
--- a/samples/client/petstore/cpp-qt/client/PFXPet.h
+++ b/samples/client/petstore/cpp-qt/client/PFXPet.h
@@ -35,13 +35,13 @@ class PFXTag;
 class PFXPet : public PFXObject {
 public:
     PFXPet();
-    PFXPet(QString json);
+    PFXPet(const QString &json);
     ~PFXPet() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt/client/PFXTag.cpp b/samples/client/petstore/cpp-qt/client/PFXTag.cpp
index ea32dc814765..255653d5f7a0 100644
--- a/samples/client/petstore/cpp-qt/client/PFXTag.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXTag.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXTag::PFXTag(QString json) {
+PFXTag::PFXTag(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -40,7 +40,7 @@ void PFXTag::initializeModel() {
     m_name_isValid = false;
 }
 
-void PFXTag::fromJson(QString jsonString) {
+void PFXTag::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt/client/PFXTag.h b/samples/client/petstore/cpp-qt/client/PFXTag.h
index 808aab4519e0..5cb5196bfad7 100644
--- a/samples/client/petstore/cpp-qt/client/PFXTag.h
+++ b/samples/client/petstore/cpp-qt/client/PFXTag.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXTag : public PFXObject {
 public:
     PFXTag();
-    PFXTag(QString json);
+    PFXTag(const QString &json);
     ~PFXTag() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);
diff --git a/samples/client/petstore/cpp-qt/client/PFXTestAnyType.cpp b/samples/client/petstore/cpp-qt/client/PFXTestAnyType.cpp
index f0baa2c149e5..d5ef6d36da48 100644
--- a/samples/client/petstore/cpp-qt/client/PFXTestAnyType.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXTestAnyType.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXTestAnyType::PFXTestAnyType(QString json) {
+PFXTestAnyType::PFXTestAnyType(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -40,7 +40,7 @@ void PFXTestAnyType::initializeModel() {
     m_message_isValid = false;
 }
 
-void PFXTestAnyType::fromJson(QString jsonString) {
+void PFXTestAnyType::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt/client/PFXTestAnyType.h b/samples/client/petstore/cpp-qt/client/PFXTestAnyType.h
index b8a76d1fc964..49228ad295e2 100644
--- a/samples/client/petstore/cpp-qt/client/PFXTestAnyType.h
+++ b/samples/client/petstore/cpp-qt/client/PFXTestAnyType.h
@@ -31,13 +31,13 @@ namespace test_namespace {
 class PFXTestAnyType : public PFXObject {
 public:
     PFXTestAnyType();
-    PFXTestAnyType(QString json);
+    PFXTestAnyType(const QString &json);
     ~PFXTestAnyType() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     QJsonValue getCode() const;
     void setCode(const QJsonValue &code);
diff --git a/samples/client/petstore/cpp-qt/client/PFXUser.cpp b/samples/client/petstore/cpp-qt/client/PFXUser.cpp
index e466a42424cc..c329701733b4 100644
--- a/samples/client/petstore/cpp-qt/client/PFXUser.cpp
+++ b/samples/client/petstore/cpp-qt/client/PFXUser.cpp
@@ -20,7 +20,7 @@
 
 namespace test_namespace {
 
-PFXUser::PFXUser(QString json) {
+PFXUser::PFXUser(const QString &json) {
     this->initializeModel();
     this->fromJson(json);
 }
@@ -58,7 +58,7 @@ void PFXUser::initializeModel() {
     m_user_status_isValid = false;
 }
 
-void PFXUser::fromJson(QString jsonString) {
+void PFXUser::fromJson(const QString &jsonString) {
     QByteArray array(jsonString.toStdString().c_str());
     QJsonDocument doc = QJsonDocument::fromJson(array);
     QJsonObject jsonObject = doc.object();
diff --git a/samples/client/petstore/cpp-qt/client/PFXUser.h b/samples/client/petstore/cpp-qt/client/PFXUser.h
index 5a3def81b532..509dd5420cd5 100644
--- a/samples/client/petstore/cpp-qt/client/PFXUser.h
+++ b/samples/client/petstore/cpp-qt/client/PFXUser.h
@@ -30,13 +30,13 @@ namespace test_namespace {
 class PFXUser : public PFXObject {
 public:
     PFXUser();
-    PFXUser(QString json);
+    PFXUser(const QString &json);
     ~PFXUser() override;
 
     QString asJson() const override;
     QJsonObject asJsonObject() const override;
     void fromJsonObject(QJsonObject json) override;
-    void fromJson(QString jsonString) override;
+    void fromJson(const QString &jsonString) override;
 
     qint64 getId() const;
     void setId(const qint64 &id);