解决信号 signalRef 引用 为undefined

[Bear]

signalEventDefinition signalRef="undefined"
let signalRef = this.bpmnModeler.get('moddle').create('bpmn:Signal', {
id: 'theSignalsss',
name: 'xxx',
})

let singalEvent = this.bpmnModeler.get('moddle').create('bpmn:SignalEventDefinition', {
signalRef: signalRef,
})

this.modeling.updateProperties(elemnet, {
eventDefinitions: [singalEvent],
})

[wangpeilin]

厉害厉害୧(๑•̀◡•́๑)૭