Merge U3D via Java

//Multiple source files that need to be merged
String[] files = {"template.u3d","template2.u3d"};

//Process file merge to generate usdz file
Scene scene = new Scene();
int i = 0;

for(String file: files)
{
    FileStream fs = new FileStream(file, FileStream.OPEN, FileStream.READ);
    FileFormat fmt = FileFormat.detect(fs, files[i]);
    Node subNode = scene.getRootNode().createChildNode(files[i]);
    i++;
    try
    {
        Scene subScene = new Scene();
        LoadOptions opt = fmt.createLoadOptions();
        subScene.open(fs, opt);
        subNode.setEntity(PolygonModifier.mergeMesh(subScene));
        MoveTo(subScene.getRootNode(), subNode);
    }
    catch (Exception e)
    {
    }
}

String reviewFile = "result.usdz";
UsdSaveOptions usdz = new UsdSaveOptions(FileFormat.USDZ);
usdz.setPrimitiveToMesh(false);
usdz.setExportMetaData(true);

scene.save(reviewFile, usdz);

//Process usdz files and save them in the format you want
Scene scene2 = new Scene();
String physicalFile = reviewFile;
FileStream fs2 = new FileStream(physicalFile, FileStream.OPEN, FileStream.READ);
FileFormat fmt2 = FileFormat.detect(fs2, "result");
Scene subScene2 = new Scene();
LoadOptions opt2 = fmt2.createLoadOptions();
subScene2.open(fs2, opt2);
Node newNode = scene2.getRootNode().createChildNode("");
double[] value = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 };
newNode.getTransform().setTransformMatrix(new Matrix4(value));
MoveTo(subScene2.getRootNode(), newNode);
String output = "merger.fbx";
scene2.save(output, FileFormat.FBX7400ASCII);

//MoveTo class for call processing
public static void MoveTo(Node subScene, Node parent)
{
    while (subScene.getChildNodes().size() > 0)
    {
        Node node = subScene.getChildNodes().get(0);
        subScene.getChildNodes().remove(0);
        parent.addChildNode(node);
    }
}