code: public boolean writeIfMatching(Object o, boolean showType, Writer output)
      {
          if (neverShowType)
          {
              showType = false;
          }
          Class c = o.getClass();
          if (notCustom.contains(c))
          {
              return false;
          }
  
          try
          {
              return writeCustom(c, o, showType, output);
          }
          catch (IOException e)
          {
              throw new JsonIoException("Unable to write custom formatted object:", e);
          }
      }
docs: Write the passed in object (o) to the JSON output stream, if and only if, there is a custom
  writer associated to the Class of object (o).
  @param o Object to be (potentially written)
  @param showType boolean indicating whether or not to show @type.
  @param output Writer where the actual JSON is being written to.
  @return boolean true if written, false is there is no custom writer for the passed in object.