public boolean hasAttribute(String key) {
        return attributes().containsKey(toKey(key));
    }
@Test
    void hasAttribute() {
        final LDAPEntry entry = LDAPEntry.builder()
                .dn("cn=jane,ou=people,dc=example,dc=com")
                .base64UniqueId(Base64.encode("unique-id"))
                .addAttribute("zero", "0")
                .addAttribute("one", null)
                .build();

        assertThat(entry.hasAttribute("zero")).isTrue();
        assertThat(entry.hasAttribute("ZERO")).isTrue();
        assertThat(entry.hasAttribute("one")).isFalse();
        assertThat(entry.hasAttribute("nope")).isFalse();
    }