Avoid use of Objects.hash when there's only 1 params

- directly call #hashCode() when hashed Object seems non-null
- replace with Objects.hashCode(Object) when Nullable
- replace with Long.hashCode(long), etc. when primitive

Change-Id: I08c24ebbe94cf4162d1491209a14baf953163e41
diff --git a/core/api/src/main/java/org/onosproject/cluster/DefaultControllerNode.java b/core/api/src/main/java/org/onosproject/cluster/DefaultControllerNode.java
index 5f3e0e1..3787daa 100644
--- a/core/api/src/main/java/org/onosproject/cluster/DefaultControllerNode.java
+++ b/core/api/src/main/java/org/onosproject/cluster/DefaultControllerNode.java
@@ -20,6 +20,7 @@
 import java.util.Objects;
 
 import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * Default implementation of a controller instance descriptor.
@@ -57,7 +58,7 @@
      * @param tcpPort TCP port
      */
     public DefaultControllerNode(NodeId id, IpAddress ip, int tcpPort) {
-        this.id = id;
+        this.id = checkNotNull(id);
         this.ip = ip;
         this.tcpPort = tcpPort;
     }
@@ -79,7 +80,7 @@
 
     @Override
     public int hashCode() {
-        return Objects.hash(id);
+        return id.hashCode();
     }
 
     @Override