Refactor: Avoid using ternary operator. Remove unnecessary casting.

	* Apply suggestion in #2192 to previous implemented classes

Change-Id: I271d64202dd43968825600cd9afc49eb400371bf
diff --git a/utils/misc/src/main/java/org/onlab/packet/IPv6.java b/utils/misc/src/main/java/org/onlab/packet/IPv6.java
index 16c6687..3bb35c5 100644
--- a/utils/misc/src/main/java/org/onlab/packet/IPv6.java
+++ b/utils/misc/src/main/java/org/onlab/packet/IPv6.java
@@ -218,7 +218,10 @@
             payloadData = this.payload.serialize();
         }
 
-        this.payloadLength = payloadData == null ? 0 : (short) payloadData.length;
+        this.payloadLength = 0;
+        if (payloadData != null) {
+            this.payloadLength = (short) payloadData.length;
+        }
 
         final byte[] data = new byte[FIXED_HEADER_LENGTH + payloadLength];
         final ByteBuffer bb = ByteBuffer.wrap(data);