fix: accommodate for open api schema that do not have any 'properties'

PiperOrigin-RevId: 792028582

Author: google-genai-bot

src/google/adk/tools/_gemini_schema_util.py

@@ -120,7 +120,7 @@ def _sanitize_schema_formats_for_gemini(
       snake_case_schema[field_name] = [
           _sanitize_schema_formats_for_gemini(value) for value in field_value
       ]
-    elif field_name in dict_schema_field_names:
+    elif field_name in dict_schema_field_names and field_value is not None:
       snake_case_schema[field_name] = {
           key: _sanitize_schema_formats_for_gemini(value)
           for key, value in field_value.items()

tests/unittests/tools/test_gemini_schema_util.py

@@ -511,6 +511,14 @@ def test_sanitize_schema_formats_for_gemini_nullable(self):
         "type": "object",
     }
 
+  def test_to_gemini_schema_properties_is_none(self):
+    """Tests schema conversion when 'properties' field is None."""
+    openapi_schema = {"type": "object", "properties": None}
+    gemini_schema = _to_gemini_schema(openapi_schema)
+    assert isinstance(gemini_schema, Schema)
+    assert gemini_schema.type == Type.OBJECT
+    assert gemini_schema.properties is None
+
 
 class TestToSnakeCase: