Azure Redis Checkpoint Store Samples Issue

[Menghua1]

Section link:

Reason:
java.lang.NullPointerException: 'processError' cannot be null.

Suggestion:
Add code

            .processEvent(eventContext -> {
                System.out.println("Partition id = " + eventContext.getPartitionContext().getPartitionId() + " and "
                    + "sequence number of event = " + eventContext.getEventData().getSequenceNumber());
            })
            .processError(context -> {
                System.out.println("Error occurred while processing events " + context.getThrowable().getMessage());
            })

@sandeep-sen, @josefree, @ronniegeraghty, @jsquire and @ahsonkhan for notification.