How to resolve null pointer exception while using pubsub MessageReceiver

Question

I had java scheduler based implementation to read gcp pubsub msg but then I changed the same to use gcp pubsub MessageReceiver to listen and read msg asynchronously.

// Class that implemented MessageReceiver contains code

 @Override
    public void receiveMessage( PubsubMessage message, AckReplyConsumer ackReplyConsumer ) {
        //some code
        processMsg( message, blobs, profiler, ackConsumer );
    }
        
    private void processMsg( PubsubMessage message, Page<Blob> blobs, Profiler profiler, AckReplyConsumer ackConsumer ) {
        setContext("id");
    }
    
     private void setContext( String id ) {
        UserContext userContext = UserContext.getContext();
        // when I change implementation to- use MessageReceiver instead of scheduler, I am getting userContext=null here;
     }
     
 

//class UserContext{

 private static final ThreadLocal<UserContext> threadLocal = new ThreadLocal<UserContext>();
 
 public static UserContext getContext() {
    try {
        final UserContext userContext = threadLocal.get();
        if ( null != userContext ) {
            return (UserContext)userContext.clone();
        }
    } catch( CloneNotSupportedException e ) {
    }
    return null;
}

}

How to get userContext=notNull when we call UserContext.getContext(). I am new to thread so not sure how to resolve this null pointer.