public void call(String name,Writable json) throws IOException {
  writeName(name);
  verifyValue();
  if (json instanceof GString) {
    writer.write(JsonOutput.toJson(json.toString()));
  }
 else {
    json.writeTo(writer);
  }
}

public void call ( String name , Writable json ) throws IOException { writeName ( name ) ; verifyValue ( ) ; if ( json instanceof GString ) { writer . write ( JsonOutput . toJson ( json . toString ( ) ) ) ; } else { json . writeTo ( writer ) ; } }
writes the given writable as the value of the given attribute name
