Implemented the extension framework for selectors.

Change-Id: I577900141889fc70ca54e96cd5d54cfd5194b05d
diff --git a/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
index 5958d1f..63ee03e 100644
--- a/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
+++ b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
@@ -436,7 +436,7 @@
                         log.debug("Adding rule in store, but not on switch {}", rule);
                         flowMissing(rule);
                     } catch (Exception e) {
-                        log.debug("Can't add missing flow rule {}", e.getMessage());
+                        log.debug("Can't add missing flow rule:", e);
                         continue;
                     }
                 }