A ServiceRuntimeDescription object contains immutable data that is needed during the runtime
(i.e. to detect @Resource injection). The ServiceRuntimeDescription must be immutable so that it
can safely accessed by multiple theads without synchronization. It cannot be used to store
information that may not be available in different threads/ classloaders (i.e. it cannot have
references to Class objects)
The actual ServiceRuntimeDescription objects are accessed via the key.