anchor.diff:  
   
     /**
  -   * Returns the response headers.
  +   * Returns the client response headers.
  +   *
  +   * The client response headers are immutable.
      */
     HttpHeaders get headers;
   
  
positive.code: 
    /**
     * Returns the response headers.
     */
    HttpHeaders get headers;
  
  
negative.code:   int contentLength;
  
    /**
     * Returns the client request headers.
     *
     * The client request headers can be modified until the client
     * request body is written to or closed. After that they become
     * immutable.
     */
    HttpHeaders get headers;
  
  