@Override
    public void read(JmeImporter im) throws IOException {
        super.read(im);
        InputCapsule ic = im.getCapsule(this);
        try {
            String rootClass = ic.readString("rootClass", null);
            if (rootClass == null) throw new Exception("rootClass is undefined");
            Class<? extends Struct> rootStructClass = (Class<? extends Struct>) Class.forName(rootClass);
            Struct rootStruct = rootStructClass.newInstance();
            loadLayout(rootStruct);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
Update data and layout (when needed) using a Struct class.

@param struct
jme3-core/src/main/java/com/jme3/util/struct/StructStd140BufferObject.java