/**
     * Checks if EPSV command should be used with IPv4.
     *
     * @return True if EPSV with IPv4 is enabled, false otherwise
     */
    public boolean isUseEPSVwithIPv4() {
        return useEPSVwithIPv4;
    }

    /**
     * Sets whether EPSV command should be used with IPv4.
     *
     * @param useEPSVwithIPv4 True to enable EPSV with IPv4, false to disable
     */

 * [system DNS service][SYSTEM], which is the default. Some applications may provide their own
 * implementation to use a different DNS server, to prefer IPv6 addresses, to prefer IPv4 addresses,
 * or to force a specific known IP address.
 *
 * Implementations of this interface must be safe for concurrent use.
 */
fun interface Dns {
  /**

# Docker on Windows doesn't support the `host` networking mode, and so
# port-forwarding is required for the container to detect it's running on GCE.
export IP_ADDR=$(powershell -command "(Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias 'vEthernet (nat)').IPAddress")
netsh interface portproxy add v4tov4 listenaddress=$IP_ADDR listenport=80 connectaddress=169.254.169.254 connectport=80
# A local firewall rule for the container is added in

    }

    public void test_resolve_ipv4() throws UnknownHostException {
        IdnDnsResolver resolver = new IdnDnsResolver();

        // Test IPv4 loopback address
        String host = "127.0.0.1";
        InetAddress[] addresses = resolver.resolve(host);
        assertNotNull(addresses);
        assertTrue(addresses.length > 0);

set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Djava.awt.headless=true

REM maximum # keep-alive connections to maintain at once
set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Dhttp.maxConnections=20

REM Force the JVM to use IPv4 stack
if NOT "%FESS_USE_IPV4%" == "" (
set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Djava.net.preferIPv4Stack=true
)

REM proxy
if NOT "%FESS_PROXY_HOST%" == "" (

# "The filename, directory name, or volume label syntax is incorrect."
# In such cases, check that the name of the sub-interface is valid:
# `netsh interface show interface`
RUN netsh interface ipv4 set subinterface \"vEthernet (Ethernet)\" mtu=1460 store=persistent

RUN md C:\TEMP
RUN md C:\TMP

# Install 7-Zip.
RUN (New-Object Net.WebClient).DownloadFile('https://www.7-zip.org/a/7z2201-x64.msi', '7z.msi'); \

 * Prefer to alternate IP addresses from different address families, (IPv6 / IPv4), starting with IPv6.
 * Don't start a new attempt until 250 ms after the most recent attempt was started.
 * Keep whichever TCP connection succeeds first and cancel all the others.

        private final int flags;
        
        public static final int IPV4 = 0x01;
        public static final int IPV6 = 0x02;
        
        public WitnessIPAddress(InetAddress address) {
            this.address = address;
            this.flags = address.getAddress().length == 4 ? IPV4 : IPV6;
        }
        
        public InetAddress getAddress() { return address; }

          }

          call.eventListener.dnsEnd(call, socketHost, result)
          result
        }

      // Try each address for best behavior in mixed IPv4/IPv6 environments.
      val orderedAddresses =
        when {
          fastFallback -> reorderForHappyEyeballs(addresses)
          else -> addresses
        }

      for (inetAddress in orderedAddresses) {

| com.squareup.okhttp3:mockwebserver:5.0.0         | okhttp3.mockwebserver | Obsolete. Depends on JUnit 4.     |

**OkHttp now supports Happy Eyeballs ([RFC 8305][rfc_8305]) for IPv4+IPv6 networks.** It attempts
both IPv6 and IPv4 connections concurrently, keeping whichever connects first.

**We’ve improved our Kotlin APIs.** You can skip the builder:

```kotlin
val request = Request(