Introduced JsonTree data structure (incl. tests) and JsonProcessingException.
Split IJsonSerializer into IMapJsonSerializer and ITreeJsonSerializer.
JsonTreeNodeTest: Ensure that getChildren returns a copy of the internal data children map.
Introduced IJsonTreeVisitor, a visitor for IJsonTreeElements.
Introducing JsonSerializationVisitor and JsonTreeFlattenVisitor which provide convenience functionality probably used often in the context of serialization of IJsonTreeElement structures.
Corrected documentation. Moved from ITreeJsonSerializer to  IMapJsonSerializer.
Moved all JSON related code to piltover.dependencies.json package.
Test: Introduced ExpectedMethodCalledException which indicates that a certain expected method was called. Is used now in JsonSerializationVisitorTest and JsonTreeFlattenVisitorTest instead of internal AcceptVisitorException class which was used for the same purpose.
Added tests for the acceptVisitor() method of JsonTreeLeaf and JsonTreeNode.
Removed obsolete imports.