Tag nullable arguments in main header. Fixes #309

Nullable arguments will be added to the `introspect` datastructures in a future change.

PiperOrigin-RevId: 789350522
Change-Id: I0bfd12fab5121f94b937264570f907593b63cf64

python/mujoco/introspect/codegen/generate_functions.py

@@ -95,7 +95,11 @@ class MjFunctionVisitor:
     else:
       strings = []
       for child in node['inner']:
-        strings.append(self._make_comment(child))
+        comment = self._make_comment(child)
+        nullable_index = comment.find('Nullable:')
+        if nullable_index != -1:
+          comment = comment[:nullable_index]
+        strings.append(comment)
       return ''.join(strings)
 
   def visit(self, node: ClangJsonNode) -> None: