This rule flags the use of following constructors.
java.net.Socket(Proxy proxy)java.net.DatagramSocket(SocketAddress bindaddr)java.net.MulticastSocket(SocketAddress bindaddr)The legacy implementation of SocketImpl has not been used by default since JDK 13, while the legacy implementation of DatagramSocketImpl has not been used by default since JDK 15. To reduce the risk of switching the implementation after more than twenty years, the old implementation will not be removed. The JDK-specific system property to switch to the old implementations are jdk.net.usePlainSocketImpl and jdk.net.usePlainDatagramSocketImpl for SocketImpl and DatagramSocketImpl respectively.
For more information see JDK-8253119.