fix nexus-service-bean explicitConfig support

[mnichols]

It is not possible to register Nexus services via explicit config today (nexus-service-beans).

Expected Behavior

@Service implementations should be registered on a Temporal Worker without using AutoConfiguration (aka explicit configuration).

The problem is, Nexus Spring registration is not fully tested.
This config fails in ExplicitConfigTest

spring:
  config:
    activate:
      on-profile: explicit-config
  temporal:
    workers:
      - task-queue: UnitTest
        workflow-classes:
          - io.temporal.spring.boot.autoconfigure.bytaskqueue.TestWorkflowImpl
        activity-beans:
          - TestActivityImpl
       # this should register the service impl but fails. See stack trace
        nexus-service-beans:
          - TestNexusServiceImpl

Actual Behavior

When bringing up a worker doing explicit config only (spring), the @ServiceImpl attribute is not found while registering the service even when the attribute is present and correct.

Caused by:
                java.lang.IllegalArgumentException: Missing @ServiceImpl annotation
                    at io.nexusrpc.handler.ServiceImplInstance.fromInstance(ServiceImplInstance.java:25)
                    at io.temporal.spring.boot.autoconfigure.template.WorkersTemplate.lambda$createWorkerFromAnExplicitConfig$7(WorkersTemplate.java:400)

Steps to Reproduce the Problem

1. Actually use explicit config with Nexus somewhere in tests that has nexus-service-beans.

The problem is we are using AopUtils to unpack the bean before getting the @serviceImpl definition but that is passing the class, not the implementation.

The fix is to just pass the bean in directly and tests pass.

Specifications

• Version:
• Platform:
  stack.txt

See tests

[Quinn-With-Two-Ns]

Note, this will require SDK team approval

[mnichols]

By the way, if you need to workaround this bug right now you can just autodiscover on the services package (if you've isolated your Nexus services) and do explicit config for the rest. Eg

  temporal:
    connection:
      # Connection settings
      target: ${TEMPORAL_ADDRESS:localhost:7233}

      # API Key for Temporal Cloud
      api-key: ${TEMPORAL_API_KEY:}

    start-workers: true
    namespace: ${TEMPORAL_NAMESPACE:default}
    workers:
      - task-queue: processing
        workflow-classes:
          - com.acme.processing.workflows.OrderImpl
#        nexus-service-beans:
#          - processing-service
    workers-auto-discovery:
      packages: com.acme.processing.services
      ```