Reuse of ActivityStubs from another workflow should produce a usable diagnostic or be allowed

Expected Behavior

ActivityStubs should be created for each workflow instance / execution separately.

But if somebody uses Dependency Injection frameworks with Temporal it's very easy to misconfigure the wiring (for example, by making them lazily initialized on first usage singletons) in a way that activity stubs will be leaking between workflow instances.
We should detect or provide better protection or diagnostic if this happens that actually helps to understand the problem.

Actual Behavior

Cryptic Event Loop error that makes to look in a completely wrong direction.

        Caused by:
        io.temporal.failure.ApplicationFailure: message='Operation allowed only while eventLoop is running', type='java.lang.IllegalStateException', nonRetryable=false
            at io.temporal.internal.statemachines.WorkflowStateMachines.checkEventLoopExecuting(WorkflowStateMachines.java:915)
            at io.temporal.internal.statemachines.WorkflowStateMachines.randomUUID(WorkflowStateMachines.java:611)
            at io.temporal.internal.replay.ReplayWorkflowContextImpl.randomUUID(ReplayWorkflowContextImpl.java:93)
            at io.temporal.internal.sync.SyncWorkflowContext.constructExecuteLocalActivityParameters(SyncWorkflowContext.java:351)
            at io.temporal.internal.sync.SyncWorkflowContext.executeLocalActivityOnce(SyncWorkflowContext.java:292)
            at io.temporal.internal.sync.SyncWorkflowContext.executeLocalActivityOnce(SyncWorkflowContext.java:275)
            at io.temporal.internal.sync.SyncWorkflowContext.lambda$executeLocalActivity$a6925f48$1(SyncWorkflowContext.java:269)
            at io.temporal.internal.sync.WorkflowRetryerInternal.retryAsync(WorkflowRetryerInternal.java:232)
            at io.temporal.internal.sync.SyncWorkflowContext.executeLocalActivity(SyncWorkflowContext.java:268)
            at io.temporal.common.interceptors.WorkflowOutboundCallsInterceptorBase.executeLocalActivity(WorkflowOutboundCallsInterceptorBase.java:48)
            at io.temporal.opentracing.internal.OpenTracingWorkflowOutboundCallsInterceptor.executeLocalActivity(OpenTracingWorkflowOutboundCallsInterceptor.java:70)
            at io.temporal.internal.sync.LocalActivityStubImpl.executeAsync(LocalActivityStubImpl.java:50)
            at io.temporal.internal.sync.ActivityStubBase.execute(ActivityStubBase.java:38)
            at io.temporal.internal.sync.LocalActivityStubImpl.execute(LocalActivityStubImpl.java:29)
            at io.temporal.internal.sync.LocalActivityInvocationHandler.lambda$getActivityFunc$0(LocalActivityInvocationHandler.java:72)
            at io.temporal.internal.sync.ActivityInvocationHandlerBase.invoke(ActivityInvocationHandlerBase.java:70)
            at com.sun.proxy.$Proxy158.execute(Unknown Source:0)
            <!-- a project specific workflow code -->
            at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method:0)
            at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
            at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
            at java.base/java.lang.reflect.Method.invoke(Method.java:566)
            at io.temporal.internal.sync.POJOWorkflowImplementationFactory$POJOWorkflowImplementation$RootWorkflowInboundCallsInterceptor.execute(POJOWorkflowImplementationFactory.java:321)
            at io.temporal.common.interceptors.WorkflowInboundCallsInterceptorBase.execute(WorkflowInboundCallsInterceptorBase.java:37)
            at io.temporal.opentracing.internal.OpenTracingWorkflowInboundCallsInterceptor.execute(OpenTracingWorkflowInboundCallsInterceptor.java:72)
            at io.temporal.internal.sync.POJOWorkflowImplementationFactory$POJOWorkflowImplementation.execute(POJOWorkflowImplementationFactory.java:295)
            at io.temporal.internal.sync.WorkflowExecuteRunnable.run(WorkflowExecuteRunnable.java:53)
            at io.temporal.internal.sync.SyncWorkflow.lambda$start$0(SyncWorkflow.java:131)
            at io.temporal.internal.sync.CancellationScopeImpl.run(CancellationScopeImpl.java:101)
            at io.temporal.internal.sync.WorkflowThreadImpl$RunnableWrapper.run(WorkflowThreadImpl.java:110)
            at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
            at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
            at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
            at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
            at java.base/java.lang.Thread.run(Thread.java:829)

This specific issue happened with DI wiring using Dagger

Alternative

There is no reason for ActivityStub that is a pair of ActivityType, ActivityOptions to don't be workflow context-independent. We can make internal changes to make them safely shareable, which is probably a better user experience.

Start with ActivityStubBase, LocalActivityStubImpl, and the WorkflowStateMachines.checkEventLoopExecuting path shown in the stack trace. Reproduce the failure with ActivityStubs shared across workflow instances, including the described Dagger wiring. Done means the misuse produces a useful diagnostic or the stub can be safely shared, with regression coverage for the chosen behavior.