public JsonToken nextToken() throws IOException
{
if (_currentReader == null) {
int index = _decoder.readIndex();
if (index < 0 || index >= _memberReaders.length) {
throw new JsonParseException("Invalid index ("+index+"); union only has "
+_memberReaders.length+" types",
_parser.getCurrentLocation());
}
// important: remember to create new instance
// also: must pass our parent (not this instance)