Replace manual hash code calculation for long with Long.hashCode(long)

Change-Id: Ie588a2904e0fcc790282af22912e8ff6d7a31648

@@ -60,7 +60,7 @@ public final class IntentId {
 
     @Override
     public int hashCode() {
-        return (int) (value ^ (value >>> 32));
+        return Long.hashCode(value);
     }
 
     @Override

@@ -42,7 +42,7 @@ public abstract class Key {
 
     @Override
     public int hashCode() {
-        return (int) (hash() ^ (hash() >>> 32));
+        return Long.hashCode(hash);
     }
 
     @Override

@@ -65,7 +65,7 @@ public final class TunnelId {
 
     @Override
     public int hashCode() {
-        return (int) (value ^ (value >>> 32));
+        return Long.hashCode(value);
     }
 
     @Override

@@ -91,9 +91,7 @@ public final class Dpid {
 
     @Override
     public int hashCode() {
-        int hash = 17;
-        hash += 31 * hash + (int) (value ^ value >>> 32);
-        return hash;
+        return Long.hashCode(value);
     }
 
     /**

@@ -81,8 +81,6 @@ public final class ChassisId {
 
     @Override
     public int hashCode() {
-        int hash = 17;
-        hash += 31 * hash + (int) (value ^ value >>> 32);
-        return hash;
+        return Long.hashCode(value);
     }
 }