// Test multiple different types in sequence to ensure type safety
        OptionalEntity<String> stringOpt = OptionalUtil.ofNullable("string");
        OptionalEntity<Integer> intOpt = OptionalUtil.ofNullable(42);
        OptionalEntity<Boolean> boolOpt = OptionalUtil.ofNullable(true);
        OptionalEntity<Date> dateOpt = OptionalUtil.ofNullable(new Date());

        assertTrue(stringOpt.isPresent());
        assertTrue(intOpt.isPresent());

        OptionalUtil.ofNullable(user.getTelephoneNumber())
                .filter(StringUtil::isNotBlank)
                .ifPresent(s -> entry.put(new BasicAttribute(fessConfig.getLdapAttrTelephoneNumber(), s)));
        OptionalUtil.ofNullable(user.getHomePhone())
                .filter(StringUtil::isNotBlank)
                .ifPresent(s -> entry.put(new BasicAttribute(fessConfig.getLdapAttrHomePhone(), s)));