Catch Exceptions, not Throwable to remove blockers found in SonarQube

Change-Id: I49ab731ce0c9950b55063e2afa4ce9226a7b6b4a

@@ -400,7 +400,7 @@ public class FlowRuleManager
                             extraneousFlow(rule);
                         }
                     }
-                } catch (Throwable e) {
+                } catch (Exception e) {
                     log.debug("Can't process added or extra rule {}", e.getMessage());
                     continue;
                 }
@@ -409,7 +409,7 @@ public class FlowRuleManager
                 try {
                     // there are rules in the store that aren't on the switch
                     flowMissing(rule);
-                } catch (Throwable e) {
+                } catch (Exception e) {
                     log.debug("Can't add missing flow rule {}", e.getMessage());
                     continue;
                 }

@@ -102,8 +102,8 @@ public class NettyMessagingManager implements MessagingService {
             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();

@@ -103,7 +103,7 @@ public abstract class SelectorLoop implements Runnable {
         state = State.STARTING;
         try {
             loop();
-        } catch (Throwable e) {
+        } catch (Exception e) {
             error = e;
             log.error("Loop aborted", e);
         }