src/main/java/com/googlecode/objectify/impl/SaverImpl.java
@Override
	public <E> Result<Key<E>> entity(final E entity) {
		final Result<Map<Key<E>, E>> base = this.<E>entities(Collections.singleton(entity));

		return new ResultWrapper<Map<Key<E>, E>, Key<E>>(base) {
			private static final long serialVersionUID = 1L;

			@Override
			protected Key<E> wrap(final Map<Key<E>, E> base) {
				return base.keySet().iterator().next();
			}
		};
	}
@Override
	public <E> Result<Key<E>> entity(final E entity) {
		final Result<Map<Key<E>, E>> base = this.<E>entities(Collections.singleton(entity));

		return new ResultWrapper<Map<Key<E>, E>, Key<E>>(base) {
			private static final long serialVersionUID = 1L;

			@Override
			protected Key<E> wrap(final Map<Key<E>, E> base) {
				return base.keySet().iterator().next();
			}
		};
	}
/* (non-Javadoc)
@see com.googlecode.objectify.cmd.Saver#entity(java.lang.Object)