synchronized (this.domainsLock) {
            final Map<String, Map<String, CacheEntry<DfsReferralDataInternal>>> domains = getTrustedDomains(tf);
            if (domains == null) {
                return false;
            }
            domain = domain.toLowerCase(Locale.ROOT);
            return domains.get(domain) != null;
        }
    }

        if (domains == null) {
            return false;
        }
        domain = domain.toLowerCase();
        return domains.get(domain) != null;
    }

    /**
     * Gets a domain controller transport for the specified domain
     * @param domain the domain name
     * @param auth the authentication credentials
     * @return an SMB transport to the domain controller

Public Domain...

* **TCP doesn't know about "domains"**. Only about IP addresses.
    * The information about the **specific domain** requested goes in the **HTTP data**.
* The **HTTPS certificates** "certify" a **certain domain**, but the protocol and encryption happen at the TCP level, **before knowing** which domain is being dealt with.

    class EdgeCasesTests {

        @ParameterizedTest
        @NullAndEmptySource
        @DisplayName("Should handle null and empty domains")
        void testNullAndEmptyDomains(String domain) {
            referralData.setDomain(domain);
            assertEquals(domain, referralData.getDomain());
        }

        @ParameterizedTest
        @NullAndEmptySource

        public LsarTrustInformation[] domains;
        /** Maximum count of domains. */
        public int max_count;

        @Override
        public void encode(NdrBuffer _dst) throws NdrException {
            _dst.align(4);
            _dst.enc_ndr_long(this.count);
            _dst.enc_ndr_referent(this.domains, 1);
            _dst.enc_ndr_long(this.max_count);

            if (this.domains != null) {

            }
            rpc.domains = new lsarpc.LsarRefDomainList();
            rpc.domains.count = 1;
            rpc.domains.max_count = 1;
            rpc.domains.domains = new lsarpc.LsarTrustInformation[1];
            rpc.domains.domains[0] = new lsarpc.LsarTrustInformation();
            rpc.domains.domains[0].name = new UnicodeString("", false);
            rpc.domains.domains[0].sid = new jcifs.dcerpc.rpc.sid_t();

        public LsarTrustInformation[] domains;
        /** Maximum count of domains. */
        public int max_count;

        @Override
        public void encode(NdrBuffer _dst) throws NdrException {
            _dst.align(4);
            _dst.enc_ndr_long(count);
            _dst.enc_ndr_referent(domains, 1);
            _dst.enc_ndr_long(max_count);

            if (domains != null) {

        serverData1.sflags = (byte) 0x11;
        serverData1.smaxMpxCount = 100;
        serverData1.oemDomainName = "DOMAIN1";
        serverData1.encryptedPasswords = true;

        serverData2.sflags = (byte) 0x22;
        serverData2.smaxMpxCount = 200;
        serverData2.oemDomainName = "DOMAIN2";
        serverData2.encryptedPasswords = false;

        // Then - instances should be independent

    }

    @ParameterizedTest
    @MethodSource("domains")
    @DisplayName("getUserDomain handles null and empty")
    void getUserDomain_edges(String domain) {
        TestCredentials creds = new TestCredentials(domain, false, false, new Subject(), false);
        assertEquals(domain, creds.getUserDomain());
    }

    static Stream<String> domains() {
        return Stream.of(null, "", "SALES");
    }