상속: IDocumentExecuter
 public async Task<ExecutionResult> Execute(
   Schema schema,
   object rootObject,
   string query,
   string operationName = null,
   Inputs inputs = null)
 {
     var executer = new DocumentExecuter();
     return await executer.ExecuteAsync(schema, rootObject, query, operationName);
 }
 public GraphQlExecuter(MessageLogger logger)
 {
     this.logger = logger;
     executer = new DocumentExecuter();
     writer = new DocumentWriter();
 }