code: @API(status = EXPERIMENTAL)
      public String format(final List<String> lines) {
          return String.join("\n", lines);
      }
docs: Renders an HTTP-like message into a printable string.
  
  @param lines lines of an HTTP message
  @return the whole message as a single string, separated by new lines
  @see #prepare(Precorrelation, HttpRequest)
  @see #prepare(Correlation, HttpResponse)
  @see StructuredHttpLogFormatter#format(Map)