public static int validateValidHeaderValue(CharSequence value) {
        int length = value.length();
        if (length == 0) {
            return -1;
        }
        if (value instanceof AsciiString) {
            return verifyValidHeaderValueAsciiString((AsciiString) value);
        }
        return verifyValidHeaderValueCharSequence(value);
    }
@Test
    void emptyValuesHaveNoIllegalCharsAsciiString() {
        assertEquals(-1, validateValidHeaderValue(AsciiString.EMPTY_STRING));
    }