docs: private Map<String, Object> mkExtensions(Throwable exception) {
          Map<String, Object> extensions = null;
          if (exception instanceof GraphQLError) {
              Map<String, Object> map = ((GraphQLError) exception).getExtensions();
              if (map != null) {
                  extensions = new LinkedHashMap<>();
                  extensions.putAll(map);
              }
          }
          return extensions;
      }