@Override
    public void read(JmeImporter im) throws IOException {
        InputCapsule ic = im.getCapsule(this);
        leftVariable = (ShaderNodeVariable) ic.readSavable("leftVariable", null);
        rightVariable = (ShaderNodeVariable) ic.readSavable("rightVariable", null);
        rightExpression = ic.readString("rightExpression", null);
        condition = ic.readString("condition", "");
        leftSwizzling = ic.readString("leftSwizzling", "");
        rightSwizzling = ic.readString("rightSwizzling", "");
    }
jme serialization (not used)

@param im the importer
@throws IOException from the importer
jme3-core/src/main/java/com/jme3/shader/VariableMapping.java