A recent Jira, https://issues.apache.org/jira/browse/UIMA-5698 changed how type systems are committed, by adding features to types that were found in the JCas class definition but were missing in the type system.
This was done to help a use case where JCas classes are loaded, once, but used for different versions of type system definitions, having different numbers of features. The trouble with this is that it breaks several serializations (where the type system is required to be "known", for example Cas Complete serialization), because the layout of the serialized format is with respect to the type system which created the serialization. I'm not sure what a reasonable solution to this issue is; thoughts welcomed :-) -Marshall
