--- old/src/jdk.net/share/classes/jdk/net/RdmaSockets.java	2018-12-04 20:00:05.272032570 +0000
+++ new/src/jdk.net/share/classes/jdk/net/RdmaSockets.java	2018-12-04 20:00:05.027910570 +0000
@@ -36,11 +36,7 @@
 import java.nio.channels.SocketChannel;
 import java.nio.channels.spi.SelectorProvider;
 import java.io.IOException;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Map;
-import java.util.Set;
+import java.util.Objects;
 import jdk.internal.net.rdma.RdmaPollSelectorProvider;
 import jdk.internal.net.rdma.RdmaSocketProvider;
 
@@ -50,7 +46,7 @@
  * <p>The {@link #openSocket(ProtocolFamily family) openSocket} and {@link
  * #openServerSocket(ProtocolFamily family) openServerSocket} methods
  * create RDMA-based TCP sockets.
- * 
+ *
  * <p>The {@link #openSelector() openSelector}, {@link
  * #openSocketChannel(ProtocolFamily family) openSocketChannel}, and {@link
  * #openServerSocketChannel(ProtocolFamily family) openServerSocketChannel}
@@ -65,7 +61,7 @@
  * {@link java.nio.channels.spi.SelectorProvider#openPipe openPipe} methods
  * throw {@link java.lang.UnsupportedOperationException
  * UnsupportedOperationException}.
- * 
+ *
  * @since 12
  */
 public class RdmaSockets {
@@ -98,8 +94,7 @@
      *         but IPv6 is not enabled on the platform.
      */
     public static Socket openSocket(ProtocolFamily family) throws IOException {
-        if(family == null)
-            throw new NullPointerException("protocol family is null");
+        Objects.requireNonNull("protocol family is null");
         return RdmaSocketProvider.openSocket(family);
     }
 
@@ -128,8 +123,7 @@
      */
     public static ServerSocket openServerSocket(ProtocolFamily family)
             throws IOException {
-        if(family == null)
-            throw new NullPointerException("protocol family is null");
+        Objects.requireNonNull("protocol family is null");
         return RdmaSocketProvider.openServerSocket(family);
     }
 
@@ -163,8 +157,7 @@
      */
     public static SocketChannel openSocketChannel(ProtocolFamily family)
             throws IOException {
-        if(family == null)
-            throw new NullPointerException("protocol family is null");
+        Objects.requireNonNull("protocol family is null");
         SelectorProvider provider = RdmaPollSelectorProvider.provider();
         return ((RdmaPollSelectorProvider)provider).openSocketChannel(family);
     }
@@ -194,13 +187,12 @@
      */
     public static ServerSocketChannel openServerSocketChannel(
             ProtocolFamily family) throws IOException {
-        if(family == null)
-            throw new NullPointerException("protocol family is null");
+        Objects.requireNonNull("protocol family is null");
         SelectorProvider provider = RdmaPollSelectorProvider.provider();
         return ((RdmaPollSelectorProvider)provider)
                 .openServerSocketChannel(family);
     }
- 
+
     /**
      * Opens a selector to multiplex selectable channels to RDMA sockets.
      *