Can't get the BpmnLabel object


#1

Hi, I want to set the coordinates of a BpmnLabel, when I try to get the object it returns null. I can get the BpmnShape with getDiagramElement(), also the name of the element, and I confirm there is a bpmndi:BPMNLabel in BpmnShape.
here is my code:

StartEvent start = modelInstance.getModelElementById("start");
System.out.println("startEvent name : " + start.getName());
System.out.println(start.getDiagramElement());
System.out.println(start.getDiagramElement().getBpmnLabel());

and the console info:

startEvent name : 开始
org.camunda.bpm.model.bpmn.impl.instance.bpmndi.BpmnShapeImpl@147ed70f
null
Exception in thread "main" java.lang.NullPointerException
	at com.richfit.workflow.process.PlanProcessGenerator.setStartLabelY(PlanProcessGenerator.java:337)
	at com.richfit.workflow.process.PlanProcessGenerator.generateProcess(PlanProcessGenerator.java:67)
	at com.richfit.workflow.process.PlanProcessGenerator.main(PlanProcessGenerator.java:42)

Anyone help ?
Thanks.