@Override
	public DataType toDataType() throws DuplicateNameException, IOException {
		Structure structure = (Structure) super.toDataType();
		try {
			structure.setName("boot_img_hdr_v4");
		}
		catch (InvalidNameException e) {
			//ignore
		}
		structure.add(DWORD, "signature_size", null);
		return structure;
	}
https://android.googlesource.com/platform/system/tools/mkbootimg/+/refs/heads/master/include/bootimg/bootimg.h#397
Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/android/bootimg/BootImageHeaderV4.java