JsonModelGen does not work with the latest gltf schema

[kirillp]

if I set urlString to latest glTF.schema.json the generator crashes with NPE.

The old urlString does not work either.

[javagl]

As mentioned in the README: The generator is not really intended for public use, and very narrowly focused on generating the classes for glTF based on JSON schema 3. There also is a long-standing issue about updating the glTF JSON schema to a more recent version, at KhronosGroup/glTF#929 - the last comment talks about draft 7, but I'm admittedly not entirely up to date here.

However, of course it should be possible to use the generator as simply as possible (and of course, also for other JSON schemas beyond glTF, although this raises many, many questions about the desired degree of configurability). And of course, at the very least, it should support the current glTF schema, regardless of the version.

So I'll have a look at this ASAP.

[javagl]

The latest changes added support for JSON schema 2020-12, which is currently used in glTF.

Specifically, I took care to make sure that the (newly introduced) JsonModelGenGltfCore class can be run on the current schema, and generate the expected output.