public static String toUpperCase(String in) {
        return in.toUpperCase(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