nnbd - fix

Author: vasilich6107

lib/schema/graphql_query.dart

@@ -18,7 +18,7 @@ abstract class GraphQLQuery<T, U extends JsonSerializable> extends Equatable {
   final String? operationName = null;
 
   /// Parses a JSON map into the response type.
-  T parse(Map<String, dynamic>? json);
+  T parse(Map<String, dynamic> json);
 
   /// Get variables as a JSON map.
   Map<String, dynamic> getVariablesMap() => variables?.toJson() ?? {};