@Override
    public void write(JmeExporter e) throws IOException {
        OutputCapsule capsule = e.getCapsule(this);
        capsule.write(r, "r", 0);
        capsule.write(g, "g", 0);
        capsule.write(b, "b", 0);
        capsule.write(a, "a", 0);
    }
Serialize this color 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/ColorRGBA.java