public static String toLowerCase(String in) {
        if (in.indexOf(upperIwithDot) != -1) {
            return in.replace(upperIwithDot, 'I').toLowerCase(Locale.ENGLISH);
        }
        return in.toLowerCase(Locale.ENGLISH);
    }
Return a lowercased version of the given string. Since this is language
independent, this is more of a case normalization operation than
lowercasing. Vespa code should <i>never</i> do lowercasing with implicit
locale.

@param in a string to lowercase
@return a string containing only lowercase character
vespajlib/src/main/java/com/yahoo/text/Lowercase.java