Added Host related memos.

Change-Id: Idbbce6a72b6f7fecc6691f2af68f4ce40b58ca34
diff --git a/core/api/src/main/java/org/onlab/onos/net/host/PortAddresses.java b/core/api/src/main/java/org/onlab/onos/net/host/PortAddresses.java
index 728d922..4804daf 100644
--- a/core/api/src/main/java/org/onlab/onos/net/host/PortAddresses.java
+++ b/core/api/src/main/java/org/onlab/onos/net/host/PortAddresses.java
@@ -17,6 +17,7 @@
 public class PortAddresses {
 
     private final ConnectPoint connectPoint;
+    // TODO: Should this be IpAddress or IpPrefix?
     private final Set<IpPrefix> ipAddresses;
     private final MacAddress macAddress;