wffweb/src/main/java/com/webfirmframework/wffweb/util/CharsetUtil.java
public static char[] getLowerCaseCharset(final int upto) {
        final int uptoPlusOne = upto + 1;
        final char[] characters = CHACHED_LOWER_CASE_CHARSETS.get(uptoPlusOne);
        if (characters != null) {
            return characters;
        }
        final char[] charset = new char[uptoPlusOne];
        char index = 0;
        while (index < uptoPlusOne) {
            charset[index] = Character.toLowerCase(index);
            index++;
        }
        final char[] previous = CHACHED_LOWER_CASE_CHARSETS
                .putIfAbsent(uptoPlusOne, charset);
        if (previous != null) {
            return previous;
        }
        return charset;
    }
public static char[] getLowerCaseCharset(final int upto) {
        final int uptoPlusOne = upto + 1;
        final char[] characters = CHACHED_LOWER_CASE_CHARSETS.get(uptoPlusOne);
        if (characters != null) {
            return characters;
        }
        final char[] charset = new char[uptoPlusOne];
        char index = 0;
        while (index < uptoPlusOne) {
            charset[index] = Character.toLowerCase(index);
            index++;
        }
        final char[] previous = CHACHED_LOWER_CASE_CHARSETS
                .putIfAbsent(uptoPlusOne, charset);
        if (previous != null) {
            return previous;
        }
        return charset;
    }
gets the char array of lower case chars from 0 to the given {@code upto}
value.

@param upto
@return
@since 1.0.0
@author WFF