Major Description
As we add more features for RPC and the specific codegen, there are some codegen options that should be provided as annotations on schema fields. For example, some users may want to turn binary fields into byte[], and other people may prefer ByteBuffer. Since these are codegen-scoped and not data-scoped, it would be nice to allow the properties to be "mixed in" at codegen time. By moving them out of the main schema definition, different users of the same Avro protocol could make different choices for the codegen in their specific applications.