docs: private String getRequestContent(HttpRequest request, String body) {
          StringBuilder builder = new StringBuilder();
          
          builder.append(request.getMethod());
          builder.append(" ");
          builder.append(request.getURI());
          builder.append(NEWLINE);
          
          appendHeaders(request.getHeaders(), builder);
          
          builder.append(NEWLINE);
          builder.append(body);
          
          return builder.toString(); 
      }