public float getTau() {
        return ((Point2PointConstraint) constraint).setting.tau;
    }
@param nodeA the body for the A end (not null, alias created)
@param nodeB the body for the B end (not null, alias created)
@param pivotA local translation of the joint connection point in node A
@param pivotB local translation of the joint connection point in node B
jme3-jbullet/src/main/java/com/jme3/bullet/joints/Point2PointJoint.java