Incorrect NULL handling in org.jbpm.services.task.impl.model.xml.JaxbOrganizationalEntity

Description of problem:

Ran across this while doing some code updates. Both convertListFromInterfaceToJaxbImpl and convertListFromJaxbImplToInterface fail to check for null parameter prior to creating the replacement list.

Example:
https://github.com/droolsjbpm/jbpm/blob/87cdf298d9f51173503d12c3ada4f0af8349d766/jbpm-human-task/jbpm-human-task-core/src/main/java/org/jbpm/services/task/impl/model/xml/JaxbOrganizationalEntity.java#L94

new ArrayList<OrganizationalEntity>(jaxbList.size()); will fail if jaxbList is null.

Version-Release number of selected component (if applicable):
6.0.1 and above