private static void addPreOrderJoints(Joint bone, List<Joint> addResult) {
        assert bone != null;
        addResult.add(bone);
        List<Joint> children = bone.getChildren();
        for (Joint child : children) {
            addPreOrderJoints(child, addResult);
        }
    }
Validate a model for use with DynamicAnimControl.

@param model the model to validate (not null, unaffected)
jme3-jbullet/src/main/java/com/jme3/bullet/animation/RagUtils.java