public void setZExtent(float zExtent) {
        if (zExtent < 0) {
            throw new IllegalArgumentException();
        }

        this.zExtent = zExtent;
    }
Alter the Z-axis distance between the center and the boundary.

@param zExtent the desired distance (&ge;0)
jme3-core/src/main/java/com/jme3/bounding/BoundingBox.java