I have opened a PR for implementing the KHR_lights_punctual extension for gltf:
glTF/extensions/2.0/Khronos/KHR_lights_punctual at master · KhronosGroup/glTF (github.com)
Please feel free to give feedback. I not a lighting expert, and if you see anything wrong in the implementation, please let me know.
I am currently looking for advice on implementing the
intensity field from the gltf spec into the jme lights. If you have any ideas please feel free to share them.