@Override
    public void updateModelTransform(Transform localTransform, Joint parent) {
        localTransform.toTransformMatrix(modelTransformMatrix);
        if (parent != null) {
            ((MatrixJointModelTransform) parent.getJointModelTransform()).getModelTransformMatrix().mult(modelTransformMatrix, modelTransformMatrix);
        }

    }
This JointModelTransform implementation accumulate joints transforms in a Matrix4f to properly
support non uniform scaling in an armature hierarchy
jme3-core/src/main/java/com/jme3/anim/MatrixJointModelTransform.java