code: private function parseFieldsDefinition()
      {
          // Legacy support for the SDL?
          if (! empty($this->lexer->options['allowLegacySDLEmptyFields']) &&
              $this->peek(Token::BRACE_L) &&
              $this->lexer->lookahead()->kind === Token::BRACE_R
          ) {
              $this->lexer->advance();
              $this->lexer->advance();
  
              return [];
          }
  
          return $this->peek(Token::BRACE_L)
              ? $this->many(
                  Token::BRACE_L,
                  function () {
                      return $this->parseFieldDefinition();
                  },
                  Token::BRACE_R
              )
              : new NodeList([]);
      }
docs: @return FieldDefinitionNode[]|NodeList
  
  @throws SyntaxError