Variable change causes an exception in log

[zambrovski]

Steps to reproduce

• camunda-bpm-taskpool version: 3.1.5
• Camunda BPM version: 7.15
• JDK version: 11
• Operating system: any
• Steps: Start standalone application

Copied from holunda-io/camunda-bpm-taskpool#460

Expected behaviour

• No errors.

Actual behaviour

2021-10-13 15:04:22.513  INFO 77104 --- [           main] i.h.p.e.p.a.s.PrefillingConfiguration    : Minimal process instance threshold (1) reached, starting a process.
2021-10-13 15:04:23.659 ERROR 77104 --- [           main] .p.a.RequestApprovalProcessConfiguration : <--------- CUSTOM ERROR HANDLER REPORT --------->
2021-10-13 15:04:23.683 ERROR 77104 --- [           main] .p.a.RequestApprovalProcessConfiguration : SENDER-003: Sending command GenericCommandMessage{payload={ChangeProcessVariablesForExecutionCommand(sourceReference=ProcessReference(instanceId=15c0353d-2c26-11ec-85ce-024243b99c50, executionId=15c0353d-2c26-11ec-85ce-024243b99c50, definitionId=process_approve_request:1:159b4818-2c26-11ec-85ce-024243b99c50, definitionKey=process_approve_request, name=Request Approval, applicationName=example-process-approval, tenantId=null), variableChanges=[ProcessVariableCreate(variableInstanceId=1604b84e-2c26-11ec-85ce-024243b99c50, variableName=request, revision=0, scopeActivityInstanceId=15c0353d-2c26-11ec-85ce-024243b99c50, value=PrimitiveProcessVariableValue(value=50004f87-6b15-4861-b4dc-414673d3db0b))])}, metadata={}, messageIdentifier='e3a127a9-4b7a-4e05-a0b7-92ff288d6c06', commandName='io.holunda.camunda.taskpool.api.process.variable.ChangeProcessVariablesForExecutionCommand'} resulted in error

org.axonframework.eventsourcing.eventstore.EventStoreException: An event for aggregate [15c0353d-2c26-11ec-85ce-024243b99c50] at sequence [1] was already inserted
	at org.axonframework.eventsourcing.eventstore.AbstractEventStorageEngine.handlePersistenceException(AbstractEventStorageEngine.java:123) ~[axon-eventsourcing-4.5.3.jar:4.5.3]
	at org.axonframework.eventsourcing.eventstore.jpa.JpaEventStorageEngine.lambda$appendEvents$6(JpaEventStorageEngine.java:290) ~[axon-eventsourcing-4.5.3.jar:4.5.3]
	at org.axonframework.common.transaction.TransactionManager.executeInTransaction(TransactionManager.java:47) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.eventsourcing.eventstore.jpa.JpaEventStorageEngine.appendEvents(JpaEventStorageEngine.java:283) ~[axon-eventsourcing-4.5.3.jar:4.5.3]
	at org.axonframework.eventsourcing.eventstore.AbstractEventStorageEngine.appendEvents(AbstractEventStorageEngine.java:101) ~[axon-eventsourcing-4.5.3.jar:4.5.3]
	at org.axonframework.eventsourcing.eventstore.AbstractEventStore.prepareCommit(AbstractEventStore.java:63) ~[axon-eventsourcing-4.5.3.jar:4.5.3]
	at org.axonframework.eventhandling.AbstractEventBus.doWithEvents(AbstractEventBus.java:235) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.eventhandling.AbstractEventBus.lambda$null$8(AbstractEventBus.java:155) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.messaging.unitofwork.MessageProcessingContext.notifyHandlers(MessageProcessingContext.java:72) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.messaging.unitofwork.DefaultUnitOfWork.notifyHandlers(DefaultUnitOfWork.java:106) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.messaging.unitofwork.AbstractUnitOfWork.changePhase(AbstractUnitOfWork.java:222) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.messaging.unitofwork.AbstractUnitOfWork.commitAsRoot(AbstractUnitOfWork.java:83) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.messaging.unitofwork.AbstractUnitOfWork.commit(AbstractUnitOfWork.java:71) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.messaging.unitofwork.DefaultUnitOfWork.executeWithResult(DefaultUnitOfWork.java:92) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.commandhandling.SimpleCommandBus.handle(SimpleCommandBus.java:177) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.commandhandling.SimpleCommandBus.doDispatch(SimpleCommandBus.java:143) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.commandhandling.SimpleCommandBus.dispatch(SimpleCommandBus.java:111) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.commandhandling.gateway.AbstractCommandGateway.send(AbstractCommandGateway.java:75) ~[axon-messaging-4.5.3.jar:4.5.3]
	at org.axonframework.commandhandling.gateway.DefaultCommandGateway.send(DefaultCommandGateway.java:73) ~[axon-messaging-4.5.3.jar:4.5.3]
	at io.holunda.polyflow.taskpool.sender.gateway.AxonCommandListGateway.sendToGateway(AxonCommandListGateway.kt:31) ~[classes/:na]
	at io.holunda.polyflow.taskpool.sender.process.variable.TxAwareAccumulatingProcessVariableCommandSender.send(TxAwareAccumulatingProcessVariableCommandSender.kt:108) ~[classes/:na]
	at io.holunda.polyflow.taskpool.sender.process.variable.TxAwareAccumulatingProcessVariableCommandSender.access$send(TxAwareAccumulatingProcessVariableCommandSender.kt:19) ~[classes/:na]
	at io.holunda.polyflow.taskpool.sender.process.variable.TxAwareAccumulatingProcessVariableCommandSender$send$2.afterCommit(TxAwareAccumulatingProcessVariableCommandSender.kt:55) ~[classes/:na]
	at org.springframework.transaction.support.TransactionSynchronizationUtils.invokeAfterCommit(TransactionSynchronizationUtils.java:135) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.transaction.support.TransactionSynchronizationUtils.triggerAfterCommit(TransactionSynchronizationUtils.java:123) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.triggerAfterCommit(AbstractPlatformTransactionManager.java:945) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:782) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:711) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:654) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:407) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.6.jar:5.3.6]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.6.jar:5.3.6]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) ~[spring-aop-5.3.6.jar:5.3.6]
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692) ~[spring-aop-5.3.6.jar:5.3.6]
	at io.holunda.polyflow.example.process.approval.process.RequestApprovalProcessBean$$EnhancerBySpringCGLIB$$2a9cada5.startProcess(<generated>) ~[classes/:na]
	at io.holunda.polyflow.example.process.approval.process.RequestApprovalProcessBean.startProcess$default(RequestApprovalProcessBean.kt:43) ~[classes/:na]
	at io.holunda.polyflow.example.process.approval.schedule.PrefillingConfiguration.run(PrefillingConfiguration.kt:40) ~[classes/:na]
	at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:810) ~[spring-boot-2.4.5.jar:2.4.5]
	at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:800) ~[spring-boot-2.4.5.jar:2.4.5]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:346) ~[spring-boot-2.4.5.jar:2.4.5]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1340) ~[spring-boot-2.4.5.jar:2.4.5]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1329) ~[spring-boot-2.4.5.jar:2.4.5]
	at io.holunda.polyflow.example.process.approval.SingleNodeExampleProcessApplicationKt.main(SingleNodeExampleProcessApplication.kt:68) ~[classes/:na]
Caused by: javax.persistence.TransactionRequiredException: no transaction is in progress
	at org.hibernate.internal.AbstractSharedSessionContract.checkTransactionNeededForUpdateOperation(AbstractSharedSessionContract.java:422) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.SessionImpl.checkTransactionNeededForUpdateOperation(SessionImpl.java:3397) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1354) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1349) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
	at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:311) ~[spring-orm-5.3.6.jar:5.3.6]
	at com.sun.proxy.$Proxy172.flush(Unknown Source) ~[na:na]
	at org.axonframework.eventsourcing.eventstore.jpa.JpaEventStorageEngine.lambda$appendEvents$6(JpaEventStorageEngine.java:287) ~[axon-eventsourcing-4.5.3.jar:4.5.3]
	... 41 common frames omitted