End Execution (Task Completion) Listener throwing Exception when parent process is killed. Unknown property used in expression:

Environment (Required on creation): Dev

Description (Required on creation; please attach any relevant screenshots, stacktraces, log files, etc. to the ticket):

We have a parent Camunda process which is delegating the task to another Camunda process. 

Child Camunda process itself delegating the tasks to further multiple child processes.

and all the lowest child processes are having End Execution (Task Completion)  Listener for the human Tasks.

Now before lower most child processes are completed, parent camunda process is cancelled. hence all the child processes should be cancelled. but it is throwing below exception.

Unknown property used in expression: ${lowerMostChildProcessId.TaskCompletionListner(execution)}. Cause: Cannot resolve identifier 'lowerMostChildProcessName'

Please note - 

${lowerMostChildProcessName.TaskCompletionListner(execution)}. => lowerMostChildProcessId is the name of the process.
org.camunda.bpm.engine.ProcessEngineException: Unknown property used in expression: ${lowerMostChildProcessId.TaskCompletionListner(execution)}. Cause: Cannot resolve identifier 'lowerMostChildProcessName'       at org.camunda.bpm.engine.impl.el.JuelExpression.getValue(JuelExpression.java:63)
        at org.camunda.bpm.engine.impl.el.JuelExpression.getValue(JuelExpression.java:51)
        at org.camunda.bpm.engine.impl.bpmn.listener.ExpressionExecutionListener.notify(ExpressionExecutionListener.java:38)
        at org.camunda.bpm.engine.impl.bpmn.listener.ExpressionExecutionListener.notify(ExpressionExecutionListener.java:28)
        at org.camunda.bpm.engine.impl.core.instance.CoreExecution.invokeListener(CoreExecution.java:101)
        at org.camunda.bpm.engine.impl.core.operation.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:55)
        at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:96)
        at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:128)
        at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:108)
        at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:83)
        at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:640)
        at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:614)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationDeleteCascade.execute(PvmAtomicOperationDeleteCascade.java:56)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationDeleteCascade.execute(PvmAtomicOperationDeleteCascade.java:25)

Steps to reproduce (Required on creation):

Described above.

Observed Behavior (Required on creation):

Described above.

Expected behavior (Required on creation):

End Execution (Task Completion)  Listener should executed when process is cancelled or at least it should not throw exception and there should be some way to call the task completion listener? 

Root Cause (Required on prioritization):

Solution Ideas (Optional):

Hints (optional):

Please note, we have other process where End Execution (Task Completion) mentioned. So when the process is cancelled, Camunda process calls the End Execution (Task Completion) Listener to complete the tasks after human tasks is cancelled/completed. So we are not facing any issue for normal process. issue is there only for parent-child structure processes.