private static int hexCharToNibble(char ch) {
        if (ch <= '9' && ch >= '0') {
            return ch - '0';
        } else if (ch >= 'a' && ch <= 'f') {
            return ch - 'a' + 10;
        } else if (ch >= 'A' && ch <= 'F') {
            return ch - 'A' + 10;
        }
        throw new IllegalArgumentException("Invalid hex char: " + ch);
    }
Convert a byte array into a hex string
stroom-bytebuffer/src/main/java/stroom/bytebuffer/hbase/Bytes.java