PlaceHolderLine insertMismatchPlaceholder(int index, ValidatableLine oppositeLine) {
		PlaceHolderLine placeHolder = input.createPlaceHolder(oppositeLine);
		insertLine(index, placeHolder);
		return placeHolder;
	}
A class that knows how to traverse a set a lines that are being used to generate a diff.
Ghidra/Features/Base/src/main/java/ghidra/app/util/html/diff/DiffLinesValidator.java