@Override
    public String toString() {
        return "(" + x + ", " + y + ", " + z + ", " + w + ")";
    }
Returns a string representation of the quaternion, which is unaffected.
For example, the identity quaternion is represented by:
<pre>
(0.0, 0.0, 0.0, 1.0)
</pre>

@return the string representation (not null, not empty)
jme3-core/src/main/java/com/jme3/math/Quaternion.java