private static boolean isGDTFile(ByteProvider provider) {
		if (!provider.getName().toLowerCase().endsWith(FileDataTypeManager.SUFFIX)) {
			return false;
		}
		boolean isGDT = false;
		try (InputStream inputStream = provider.getInputStream(0)) {
			isGDT = ItemSerializer.isPackedFile(inputStream);
		}
		catch (IOException e) {
			// ignore
		}
		return isGDT;
	}
Loads a packed Ghidra data type archive.
Ghidra/Features/Base/src/main/java/ghidra/app/util/opinion/GdtLoader.java