This refers to release 0.9.8, in-memory implementation (although I doubt it has influence on the bug).
I use TMAPI interface. If it is attempted to create a TopicName with exactly the same value as previously removed TopicName (using Topic.createTopicName(String, Collection)), a RuntimeException is thrown, which is initiated by a NullPointerException.
As far as I could infer, it has something to do with internal events that notify listeners (indexes probably?) that new name was created.
The relevant part of the exception stack:
Exception in thread "main" java.lang.RuntimeException: java.lang.NullPointerException
Example code to replicate the bug:
//assumed TopicMap tm is instantianated beforehand
//creating new user topic
Topic type = tm.createTopic();
Topic t = tm.createTopic();
// creating scope collection
Vector<Topic> scope = new Vector<Topic>();
// creating name t.createTopicName("name", scope);
//creating new one
t = tm.createTopic();
//RuntimeException occurs at the following line