code: void writeArrayItemStart() throws IOException {
          if (commaState.get(commaDepth)) {
              output.append(',');
              if (newLine.length() > 0) {
                  output.append(' ');
              }
          } else {
              commaState.set(commaDepth);
          }
      }
docs: Writes a JSON array item start.
  
  @throws IOException if an error occurs