IndividualDeadLetterStrategy.isDLQ() returns true if Prefix is set to empty String

Issue

• We are attempting to configure individual DLQs with a suffixed naming pattern. A queue "MY.SAMPLE" would have the DLQ "MY.SAMPLE.DLQ". Using either of the following within a
  does not achieve the desired outcome:

  <deadLetterStrategy>
    <!-- set an empty prefix -->
    <individualDeadLetterStrategy useQueueForQueueMessages="true"
                                                     queuePrefix=""
                                                     queueSuffix=".DLQ"></individualDeadLetterStrategy>
  </deadLetterStrategy>

<deadLetterStrategy>
    <individualDeadLetterStrategy useQueueForQueueMessages="true"
                                                     queuePrefix="#null"
                                                     queueSuffix=".DLQ"></individualDeadLetterStrategy>
  </deadLetterStrategy>

Setting an empty prefix results in the "parent" queue being misidentified as a DLQ.
Given the isDLQ() method is used to determine behavior in at least the following class, this would seem to be concerning org.apache.activemq.broker.region.Queue

Setting a null prefix results in the DLQs having the string null as a prefix (i.e. nullMY.SAMPLE.DLQ), see
IndividualDeadLetterStrategy.createDestination(Message,String,String,boolean,Subscription)