UIMA CasCreationUtils throws NPE when multiple threads in UIMA AS call defineCasPool

UIMA CasCreationUtils throws NPE from setupTypePriorities() when UIMA AS scales AEs in multiple threads. The NPE is due to thread safety issue in UIMA caused by lazy initialization of CAS pools. Seems to be triggered when large type system is used. Synchronize UIMA AS org.apache.uima.aae.EECasManager_impl.defineCasPool() to make sure only one thread at a time executes the code.