#186 Make all classes involved in rpc IsSerializable.
Merge branch 'master' into IsSerializable
Merge branch 'master' into IsSerializable
Merge branch 'master' into IsSerializable
Merge branch 'master' into IsSerializable
Merge branch 'master' into IsSerializable
Merge pull request #235 from HPI-Information-Systems/IsSerializable

Is serializable
Merge branch 'master' into FileIterator
#188 Convert empty strings to null values using Collections.unmodifiableList.