@Override
    public void write(JmeExporter ex) throws IOException {
        super.write(ex);
        OutputCapsule oc = ex.getCapsule(this);
        oc.write(this.volume, "volume", 1f);
        oc.write(this.lowFreqVolume, "lf_volume", 1f);
    }
Retrieves a unique identifier for this filter. Used internally for native object management.

@return a unique long identifier.
jme3-core/src/main/java/com/jme3/audio/HighPassFilter.java