/** Notifies ElementByteSizeObserver about the byte size of the encoded value using this coder. */
@Override
public void registerByteSizeObserver(
RawUnionValue union, ElementByteSizeObserver observer, Context context) throws Exception {
int index = getIndexForEncoding(union);
// Write out the union tag.
observer.update(VarInt.getLength(index));
// Write out the actual value.
@SuppressWarnings("unchecked")
Coder<Object> coder = (Coder<Object>) elementCoders.get(index);
coder.registerByteSizeObserver(union.getValue(), observer, context);
}
