void set(Quaternion rot) {
            rotation.set(rot);
            float[] a = new float[3];
            rotation.toAngles(a);
            eulerAngles.set(a[0], a[1], a[2]);
        }
the index of the parent key frame is this keyFrame is a split rotation
jme3-core/src/main/java/com/jme3/animation/AnimationFactory.java