private static int indexOfUnsafeOctet(String s, int start) {
        final int len = s.length();
        for (int i = start; i < len; i++) {
            final char c = s.charAt(i);
            if (SAFE_OCTETS[c] == 0) {
                return i;
            }
        }

        return -1;
    }
Encodes a query component (name or value). The octet at {@code start} must be an unsafe octet.
core/src/main/java/com/linecorp/armeria/internal/common/PercentEncoder.java