#455434: Bugfix for "Deserialization of entities with GSON does not work
in all JVMs"
* added default constructors in package scope
* make final field non-final where necessary

Signed-off-by: Jochen Hiller <j.hiller@telekom.de>
Merge pull request #134 from JochenHiller/Bug455434-GSON-Deserialization-correct-committer

#455434: Bugfix for "Deserialization of entities with GSON does not work in all JVMs"