private Long convertToIndex(final Long no) {
        if (no != null) {
            return no - 1;
        }
        return null;
    }
The ranges returned are line/col positions in the input text. Thus the input text should
not be changed/formatted after the highlight ranges have been generated.
stroom-core-client/src/main/java/stroom/dashboard/client/text/TextPresenter.java