code: public AsyncContext startAsync(ServletRequest servletRequest,
                                     ServletResponse servletResponse)
              throws IllegalStateException {
          return request.startAsync(servletRequest, servletResponse);
      }
docs: The default behavior of this method is to invoke
  {@link ServletRequest#startAsync(ServletRequest, ServletResponse)}
  on the wrapped request object.
  
  @param servletRequest the ServletRequest used to initialize the
  AsyncContext
  @param servletResponse the ServletResponse used to initialize the
  AsyncContext
  
  @return the (re)initialized AsyncContext
  
  @throws IllegalStateException if the request is within the scope of
  a filter or servlet that does not support asynchronous operations
  (that is, {@link #isAsyncSupported} returns false),
  or if this method is called again without any asynchronous dispatch
  (resulting from one of the {@link AsyncContext#dispatch} methods),
  is called outside the scope of any such dispatch, or is called again
  within the scope of the same dispatch, or if the response has
  already been closed
  
  @see ServletRequest#startAsync(ServletRequest, ServletResponse)
  
  @since Servlet 3.0