do not modify binding in to_apr_repr

Author: jkwlui

api_core/google/api_core/iam.py

@@ -431,8 +431,13 @@ def to_api_repr(self):
             bindings = []
             for binding in self._bindings:
                 if binding["members"]:
-                    binding["members"] = sorted(binding["members"])
-                    bindings.append(binding)
+                    new_binding = {
+                        "role": binding["role"],
+                        "members": sorted(binding["members"])
+                    }
+                    if binding.get("condition"):
+                        new_binding["condition"] = binding["condition"]
+                    bindings.append(new_binding)
 
             if bindings:
                 # Sort bindings by role