Catch Exceptions, not Throwable to remove blockers found in SonarQube

Change-Id: I49ab731ce0c9950b55063e2afa4ce9226a7b6b4a
diff --git a/utils/netty/src/main/java/org/onlab/netty/NettyMessagingManager.java b/utils/netty/src/main/java/org/onlab/netty/NettyMessagingManager.java
index bfc1c70..f550498 100644
--- a/utils/netty/src/main/java/org/onlab/netty/NettyMessagingManager.java
+++ b/utils/netty/src/main/java/org/onlab/netty/NettyMessagingManager.java
@@ -102,8 +102,8 @@
             serverChannelClass = EpollServerSocketChannel.class;
             clientChannelClass = EpollSocketChannel.class;
             return;
-        } catch (Throwable t) {
-            log.warn("Failed to initialize native (epoll) transport. Reason: {}. Proceeding with nio.", t.getMessage());
+        } catch (Exception e) {
+            log.warn("Failed to initialize native (epoll) transport. Reason: {}. Proceeding with nio.", e.getMessage());
         }
         clientGroup = new NioEventLoopGroup();
         serverGroup = new NioEventLoopGroup();