Cryptic NullPointerException when ending Sub Process with output parameters, but no outgoing arrows

[ThorbenLindhauer]

This issue was imported from JIRA:

Field	Value
JIRA Link	CAM-10580
Reporter	Lbk8JgO What is this name? This pseudonym name was generated based on the user name in JIRA to protect the personal data of our JIRA users. You can use this identifier to search for issues by the same reporter.
Has restricted visibility comments	true

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Given: Any BPMN process with a Sub Process with output parameters, but no outgoing arrows.

When: The process is started.

Then: The engine throws an exception:

Runtime result:
05-Jul-2019 12:30:55.904 SEVERE <http-nio-8080-exec-7> org.camunda.commons.logging.BaseLogger.logError ENGINE-16004 Exception while closing command context: null
 java.lang.NullPointerException
        at org.camunda.bpm.engine.impl.core.variable.mapping.OutputParameter.execute(OutputParameter.java:52)
        at org.camunda.bpm.engine.impl.core.variable.mapping.IoParameter.execute(IoParameter.java:51)
        at org.camunda.bpm.engine.impl.core.variable.mapping.IoMapping.executeOutputParameters(IoMapping.java:45)
        at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.destroy(ExecutionEntity.java:531)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationProcessEnd.eventNotificationsCompleted(PvmAtomicOperationProcessEnd.java:83)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationProcessEnd.eventNotificationsCompleted(PvmAtomicOperationProcessEnd.java:33)
        at org.camunda.bpm.engine.impl.core.operation.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:66)
(...)

Expected:

The output parameters are executed without throwing an exception.

Note:

• Attached are full logs and an example process.
• In the case of no output parameters, it works fine, without an exception.

Links:

[ThorbenLindhauer]

This comment was imported from JIRA and written by user Lbk8JgO

What is this name?

This pseudonym name was generated based on the user name in JIRA to protect the personal data of our JIRA users. You can use this identifier to search for issues by the same reporter.

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https://github.com/camunda/camunda-bpm-platform/blob/master/engine/src/main/java/org/camunda/bpm/engine/impl/core/variable/mapping/OutputParameter.java

Line 52.

It seems to me that outerScope is null in this case.

[ThorbenLindhauer]

This comment was imported from JIRA and written by user @koevskinikola

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Hi Lbk8JgO,

I have successfully replicated and understood the bug that you are reporting. I will forward it for a decision.

Best regards, Nikola

[ThorbenLindhauer]

This comment was imported from JIRA and written by user @ThorbenLindhauer

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Hello Bram,

Thanks for reporting this. I have updated the expected behavior. The ouput parameters should be executed in this case. E.g. there could be an execution listener on process level that works with them and they should show up in the history tables.

We will see if we can fix it this bug 7.12, but can't promise it. We would also be very happy to receive a contribution.

Cheers, Thorben