title: Accessing GLTF "Extension" or "Extras" property in UNITY engine
body: <p>I am currently using the SicCity GLTF importer for Unity. I have gltf files that uses the extras tag. I am having issue finding out how to access this property in UNITY. The documentation is a bit scarce.</p>
  <p>My question is how to access this property when the JSON is de-serialized in UNITY</p>