We're not willing to expose this internal method, as we have a better public alternative in 5.12:

'''java
/**
   * Returns the {@link BpmnModel} corresponding with the process definition with
   * the provided process definition id. The {@link BpmnModel} is a pojo versions
   * of the BPMN 2.0 xml and can be used to introspect the process definition
   * using regular Java.
   */
  BpmnModel getBpmnModel(String processDefinitionId);
'''