Resolves code smells of Openstack node app.

Change-Id: Ibcb17b75baa8a22a316ac259ca41adf6a9a4ef43
diff --git a/apps/openstacknode/app/src/main/java/org/onosproject/openstacknode/util/OpenstackNodeUtil.java b/apps/openstacknode/app/src/main/java/org/onosproject/openstacknode/util/OpenstackNodeUtil.java
index 277e58e..d478bcc 100644
--- a/apps/openstacknode/app/src/main/java/org/onosproject/openstacknode/util/OpenstackNodeUtil.java
+++ b/apps/openstacknode/app/src/main/java/org/onosproject/openstacknode/util/OpenstackNodeUtil.java
@@ -163,7 +163,7 @@
                 return null;
             }
         } catch (AuthenticationException e) {
-            log.error("Authentication failed due to {}", e.toString());
+            log.error("Authentication failed due to {}", e);
             return null;
         }
     }
@@ -183,6 +183,7 @@
             String s = get(properties, propertyName);
             value = Strings.isNullOrEmpty(s) ? null : Boolean.valueOf(s);
         } catch (ClassCastException e) {
+            log.error("Exception occurred because of {}. set valud to null..", e);
             value = null;
         }
         return value;
@@ -375,16 +376,21 @@
 
         TrustManager[] trustAllCerts = new TrustManager[]{
                 new X509TrustManager() {
+                    @Override
                     public X509Certificate[] getAcceptedIssuers() {
                         return null;
                     }
 
+                    @Override
                     public void checkClientTrusted(X509Certificate[] certs,
                                                    String authType) {
+                        return;
                     }
 
+                    @Override
                     public void checkServerTrusted(X509Certificate[] certs,
                                                    String authType) {
+                        return;
                     }
                 }
         };
@@ -400,7 +406,7 @@
 
             config.withSSLContext(sc);
         } catch (Exception e) {
-            log.error("Failed to access OpenStack service due to {}", e.toString());
+            log.error("Failed to access OpenStack service due to {}", e);
             return null;
         }