SONAR suggestion - generic exceptions

Replace uses of generic RuntimeException
with more appropriate unchecked exceptions

Change-Id: If283743c2cf7252b8d280bdb788708ebbe57da9d
diff --git a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFMessageEncoder.java b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFMessageEncoder.java
index 4c875ac..c541a9b 100644
--- a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFMessageEncoder.java
+++ b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFMessageEncoder.java
@@ -56,7 +56,7 @@
     @Override
     public void write(ChannelHandlerContext ctx,
                       Object msg,
-                      ChannelPromise promise) throws Exception {
+                      ChannelPromise promise) {
 
         ByteBuf buf = null;
         try {