I had an user reporting the following NPE on a test:

java.lang.NullPointerException: Cannot invoke “org.apache.activemq.artemis.utils.collections.LinkedListIterator.repeat()” because “holder.iter” is null
at org.apache.activemq.artemis.core.server.impl.QueueImpl.deliver(QueueImpl.java:3176) ~[artemis-server-2.29.0-SNAPSHOT.jar:2.29.0-SNAPSHOT]
at org.apache.activemq.artemis.core.server.impl.QueueImpl$DeliverRunner.run(QueueImpl.java:4331) ~[artemis-server-2.29.0-SNAPSHOT.jar:2.29.0-SNAPSHOT]
at org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:57) ~[artemis-commons-2.29.0-SNAPSHOT.jar:?]
at org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:32) ~[artemis-commons-2.29.0-SNAPSHOT.jar:?]
at org.apache.activemq.artemis.utils.actors.ProcessorBase.executePendingTasks(ProcessorBase.java:68) ~[artemis-commons-2.29.0-SNAPSHOT.jar:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) ~[?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) ~[?:?]

I am adding final variables so it's validated in compile time instead to avoid this particular issue.