code: public JSONEmitter startGroup(String name) {
          checkComma();
          write('"');
          write(encodeString(name));
          write("\":{");
          push();
          return this;
      }
docs: Start a new group object. The group emits the JSON:
  <pre>
  "[name]":{
  </pre>
  
  @param name  Name used for this group.
  @return      The same JSONEmitter object, which allows call chaining.