Send Meeting request plugin error

[Appian Work Item - 311072 - WorkID 382 - execution01 - process 268601395 - model 17120 : UnattendedJavaActivityRequest] ERROR com.appiancorp.process.engine.UnattendedJavaActivityRequest - An error occurred while executing activity: id=268457724, classname=com.appiancorp.ical.SendMeetingRequestActivity_v4
com.appiancorp.suiteapi.process.exceptions.SmartServiceException: Unexpected error.
	at com.appiancorp.ical.IcalUtilities.getRecipients(IcalUtilities.java:77)
	at com.appiancorp.ical.SendMeetingRequestActivity_v4.run(SendMeetingRequestActivity_v4.java:89)
	at com.appiancorp.process.runtime.framework.DefaultActivityExecutor$1.lambda$call$0(DefaultActivityExecutor.java:129)
	at com.appiancorp.plugins.PluginUsageLogger.runWithPluginInformation(PluginUsageLogger.java:54)
	at com.appiancorp.process.runtime.framework.DefaultActivityExecutor$1.call(DefaultActivityExecutor.java:129)
	at com.appiancorp.process.runtime.framework.DefaultActivityExecutor$1.call(DefaultActivityExecutor.java:123)
	at com.appiancorp.common.ContextClassLoaderSwitcher.runInContext(ContextClassLoaderSwitcher.java:30)
	at com.appiancorp.process.runtime.framework.DefaultActivityExecutor.execute(DefaultActivityExecutor.java:123)
	at com.appiancorp.process.engine.UnattendedJavaActivityRequest.execute(UnattendedJavaActivityRequest.java:110)
	at com.appiancorp.process.engine.UnattendedJavaActivityRequestResponseCreator.getJavaActivityResultResponse(UnattendedJavaActivityRequestResponseCreator.java:23)
	at com.appiancorp.process.engine.UnattendedJavaActivityRequest.getJavaActivityResultResponse(UnattendedJavaActivityRequest.java:89)
	at com.appiancorp.process.engine.UnattendedJavaActivityRequest.execute0(UnattendedJavaActivityRequest.java:72)
	at com.appiancorp.common.persistence.data.AppianDataUserContextProvider.executeWithConsistentDataReads(AppianDataUserContextProvider.java:143)
	at com.appiancorp.process.engine.ProcessContinuationRequest.executeOuter(ProcessContinuationRequest.java:68)
	at com.appiancorp.process.engine.ActivityRequest.executeOuter(ActivityRequest.java:41)
	at com.appiancorp.process.engine.ContinuationRequest.execute(ContinuationRequest.java:136)
	at com.appiancorp.process.engine.UnattendedJavaActivityRequest.execute(UnattendedJavaActivityRequest.java:125)
	at com.appiancorp.process.workpoller.UnattendedRequestHandlerBean.onMessage(UnattendedRequestHandlerBean.java:36)
	at com.appiancorp.process.workpoller.WorkItem.run(WorkItem.java:110)
	at com.appiancorp.common.spring.SimpleTaskWorkManager$DelegatingWorkAdapter.run(SimpleTaskWorkManager.java:228)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:840)