@Override
    public void write(JmeExporter e) throws IOException {
        OutputCapsule capsule = e.getCapsule(this);
        capsule.write(x, "x", 0);
        capsule.write(y, "y", 0);
        capsule.write(z, "z", 0);
        capsule.write(w, "w", 0);
    }
Serialize this vector to the specified exporter, for example when
saving to a J3O file.

@param e (not null)
@throws IOException from the exporter
jme3-core/src/main/java/com/jme3/math/Vector4f.java