code: private final State onCheckEndHeaderSection(final Buffer buffer) {
          // can't tell. We need two bytes at least to check if there is
          // more headers or not
          if (buffer.getReadableBytes() < 2) {
              return State.CHECK_FOR_END_OF_HEADER_SECTION;
          }
  
          // ok, so there was a CRLF so we are going to fetch the payload
          // if there is one...
          if (SipParser.consumeCRLF(buffer) == 2) {
              return State.GET_PAYLOAD;
          }
  
          // nope, still headers
          return State.GET_HEADER_NAME;
      }
docs: Every time we have parsed a header we need to check if there are more headers or
  if we have reached the end of the section and as such there may be a body we need
  to take care of. We know this by checking if there is a CRLF up next or not.
  
  @param buffer
  @return