private Joint findJoint(Armature armature, String jointName) {
        Joint joint = armature.getJoint(jointName);
        if (joint == null) {
            throw new IllegalArgumentException("Cannot find joint " + jointName);
        }
        return joint;
    }
Add joints to be influenced by this animation mask.

@param armature the Armature containing the joints
@param jointNames the names of the joints to be influenced

@throws IllegalArgumentException if it can not find the joint
         with the specified name on the provided armature
jme3-core/src/main/java/com/jme3/anim/ArmatureMask.java