We have jBpm workflows created in the older version of BPM. Upgrading to newer version such as 7.52.0 is assuming default value of AbortParent flag in Subprocesses as true and terminating parents of our  processes. This leads to termination of parent with subprocesses and breaking older workflows.

I looked at the implementation. When the value of abort parent is true, the implementation in bpm2 file doesn't add anything to the object, but when it is false, a code block is added. The java code things that when in a subprocess, the value is absent, it means user has set abort parent as true.

In workflows created with older versions, since the value is absent, system is assuming this value as true and terminating parents with subprocesses automatically.