Expose deserialization order for groups in Java

During development I've written a deserializer messages to json for generated classes from XML.
And I've found that Java classes requires specific order for calling methods deserializing nested groups.

It looks weird for me. I decided to annotate generated classes with order of groups in a message.

With this feature you can get pretty printed JSON representation a messages automatically.
I think this is very usefull for development and debugging easily get representation of a problem messages.

XML spec gives you only a structure. This does human representation of real data examples.

Gson jar is not packed with sbe.jar. It used only for compilation and tests.