Memory Leak in DefaultSignalManager

Every time a process is started a listener with type "processInstanceCompleted:" + processInstanceId is added by SubProcessNodeInstance.java :

private void addProcessListener() {
getProcessInstance().addEventListener("processInstanceCompleted:" + processInstanceId, this, true);
}

The a new node with key "processInstanceCompleted:" + processInstanceId is added in processEventListeners in DefaultSignalManager.java:
processEventListeners.put(type, eventListeners);

That element is never removed from processEventListeners

A Pull Request will be added to fix that