Validation button for BPMN2 needs to validate all BPMN2 spec

Current validation is minimal and based on object parsing of the bpmn2 file. The jBPM Migration tooling provides a BpmnValidator.validateDefinition(Document), we could make that a String for you.

This validates the entire process based on full bpmn2 spec.

We are cleaning up the API for this for you as discussed.