at first let me thank you for you fast response and support.
We also saw that the Unit Tests were failing, when we changed the HashMap to a ConcurrentHashMap, due to the null values you try to store, to indiciate, that no annotations were found. Synchronizing the complete block is surely a solution to the issue, but if this method is called quite often, it might get a bottleneck, because many session might be ligned up waiting to enter the method. Do you have an idea how often the method is normally called? To get around this synchronisation issue, we were thinking to use a Singleton object and put this into the Map, to indicate not annotations have been found. This surely means more changes, because every check for the null retun value nust be changed to check for this Singleton, but in regards to performance it might be the better solution.