glTF exporter: fix extension required parameter check

io_scene_gltf2/__init__.py

@@ -15,7 +15,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (1, 1, 22),
+    "version": (1, 1, 23),
     'blender': (2, 81, 6),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_gltf2_exporter.py

@@ -298,7 +298,8 @@ class GlTF2Exporter:
         if isinstance(node, gltf2_io_extensions.Extension):
             extension = self.__traverse(node.extension)
             self.__append_unique_and_get_index(self.__gltf.extensions_used, node.name)
-            self.__append_unique_and_get_index(self.__gltf.extensions_required, node.name)
+            if node.required:
+                self.__append_unique_and_get_index(self.__gltf.extensions_required, node.name)
 
             # extensions that lie in the root of the glTF.
             # They need to be converted to a reference at place of occurrence