If the activiti engine perform validation when calling DeploymentBuilder.deploy(), may I know what did it check and what happen when the process definition file is invalid?
When a process definition is deployed, it goes through our BpmnParser. There, all elements of the process will be parsed. If there are errors, these are all accumulated in a list and thrown as an exception when all the elements have been looked at.
You can check the BpmnParse file for all the lines that contain addError(…), those are validation errors.