DummyExtension should use Backend Provider

[Alexander-Krause-Glau]

I open this issue here, otherwise we will probably loose track of spread tickets.

Tl;Dr; The source code lines are necessary for extensions to convert Java to JSON-API-conform payload using the backend JSON-API providers.

The DummyExtension uses a seperate provider for JSONAPI. Since the GenericTypeFinder solves our problem of finding runtime (generic) type information, we can fully use the backend JSONAPI providers.

Use the DiscoveryExtension as example for implementing this feature. Additionally add:

GenericTypeFinder.typeMap.putIfAbsent("Timestamp", Timestamp.class);
GenericTypeFinder.typeMap.putIfAbsent("Landscape", Landscape.class);
GenericTypeFinder.typeMap.putIfAbsent("System", net.explorviz.model.System.class);
GenericTypeFinder.typeMap.putIfAbsent("NodeGroup", NodeGroup.class);
GenericTypeFinder.typeMap.putIfAbsent("Node", Node.class);
GenericTypeFinder.typeMap.putIfAbsent("Application", Application.class);
GenericTypeFinder.typeMap.putIfAbsent("Component", Component.class);
GenericTypeFinder.typeMap.putIfAbsent("Clazz", Clazz.class);
GenericTypeFinder.typeMap.putIfAbsent("CommunicationClazz", CommunicationClazz.class);
GenericTypeFinder.typeMap.putIfAbsent("Communication", Communication.class);
GenericTypeFinder.typeMap.putIfAbsent("CommunicationAccumulator", CommunicationAccumulator.class);
GenericTypeFinder.typeMap.putIfAbsent("CommunicationTileAccumulator", CommunicationTileAccumulator.class);
GenericTypeFinder.typeMap.putIfAbsent("DatabaseQuery", DatabaseQuery.class);
GenericTypeFinder.typeMap.putIfAbsent("User", User.class);

to Extension-Application constructor. GenericTypeFinder is a static class, but it seems that both applications have their own scope. Therefore, they do not share this class.

[czirkelbach]

Add three method, one as serving as a register handler for the core (registerAllCoreModels()) and two API methods as a wrapper for enabling core model types in extensions (allCoreModels() or registerAllCoreModels(Map<String, Class<?>>).

[czirkelbach]

Testing via an extension necessary

[Alexander-Krause-Glau]

Works.