Fix comments

- Delete obsolete TODO comment
- Write Javadoc for IntentUpdate subclasses which have no Javadoc

Change-Id: I2b233fa9741733fd3642bbbe639990b1ce0b7405
diff --git a/core/net/src/main/java/org/onosproject/net/intent/impl/Withdrawn.java b/core/net/src/main/java/org/onosproject/net/intent/impl/Withdrawn.java
index c7e531a..e5e4acd 100644
--- a/core/net/src/main/java/org/onosproject/net/intent/impl/Withdrawn.java
+++ b/core/net/src/main/java/org/onosproject/net/intent/impl/Withdrawn.java
@@ -21,6 +21,9 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static org.onosproject.net.intent.IntentState.WITHDRAWING;
 
+/**
+ * Represents a phase where an intent has been withdrawn.
+ */
 class Withdrawn extends CompletedIntentUpdate {
 
     private final IntentData intentData;