@Override
	public FieldLocation getFieldLocation(ListingField bf, BigInteger index, int fieldNum,
			ProgramLocation loc) {

		if (!(loc instanceof VariableNameFieldLocation)) {
			return null;
		}

		Object obj = bf.getProxy().getObject();
		if (obj instanceof Variable) {
			Variable sv = (Variable) obj;
			VariableNameFieldLocation varNameLoc = (VariableNameFieldLocation) loc;
			if (varNameLoc.isLocationFor(sv)) {
				return new FieldLocation(index, fieldNum, 0, varNameLoc.getCharOffset());
			}
		}

		return null;
	}
@see ghidra.app.util.viewer.field.FieldFactory#getFieldLocation(ghidra.app.util.viewer.field.ListingField, BigInteger, int, ghidra.program.util.ProgramLocation)
Ghidra/Features/Base/src/main/java/ghidra/app/util/viewer/field/VariableNameFieldFactory.java