@Override
	public BigInteger getIndexBefore(BigInteger index) {
		if (index.compareTo(numIndexes) > 0) {
			return numIndexes.subtract(BigInteger.ONE);
		}
		BigInteger previousIndex = index.subtract(BigInteger.ONE);
		if (previousIndex.compareTo(BigInteger.ZERO) < 0) {
			return null;
		}
		return previousIndex;
	}
@see docking.widgets.fieldpanel.LayoutModel#getIndexAfter(int)
Ghidra/Features/ByteViewer/src/main/java/ghidra/app/plugin/core/byteviewer/ByteViewerLayoutModel.java