ChangeEventHandler throws NPE at times

[vivekratnavel]

Affected module
Does it impact the UI, backend or Ingestion Framework?
Backend

Describe the bug

27.0.0.1 - - [26/Feb/2022:01:35:38 +0000] "POST /api/v1/services/dashboardServices HTTP/1.1" 201 363 "-" "Jersey/2.33 (HttpUrlConnection 11.0.12)" 4
ERROR [2022-02-26 01:35:38,406] org.openmetadata.catalog.events.ChangeEventHandler: Failed to capture change event for method POST due to 
! java.lang.NullPointerException: null
! at org.openmetadata.catalog.events.ChangeEventHandler.getThreads(ChangeEventHandler.java:186)
! at org.openmetadata.catalog.events.ChangeEventHandler.process(ChangeEventHandler.java:73)
! at org.openmetadata.catalog.events.EventFilter.lambda$filter$0(EventFilter.java:70)
! at org.openmetadata.catalog.util.ParallelStreamUtil.lambda$runAsync$0(ParallelStreamUtil.java:74)
! at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700)
! at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1692)
! at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
! at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
! at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
! at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
! at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)