public static Tween loopDuration(double duration, Tween... delegates) {
        if (delegates.length == 1) {
            return new Loop(delegates[0], duration);
        }

        return new Loop(sequence(delegates), duration);
    }
Creates a tween that loops the specified delegate tween or tweens
to the desired duration.  If more than one tween is specified then they
are wrapped in a sequence using the sequence() method.

@param duration the desired duration
@param delegates the desired sequence of tweens
@return a new instance
jme3-core/src/main/java/com/jme3/anim/tween/Tweens.java