Refactor connectivity intent creation to use builders

- Each connectivity intent now has only one constructor
- Intent constructors are now private for leaf classes and
  protected for classes that can be derived from
- Each intent class has a Builder class that accumulates
  parameters for intent creation
- Each intent class has a public static builder() method
  to create a builder
- Each Builder class has a build() method to create the
  intent from the accumulated parameters
- Added keys to a few intent types that were missing them
- Tightened up usage of checkNotNull(), taking advantage of
  the return value to save some lines of code
- Modified callers to use the builders instead of directly
  calling the constructors

Change-Id: I713185d5ecbadbf51f87ef7f68fec41102106c78
diff --git a/web/gui/src/main/java/org/onosproject/ui/impl/TopologyViewMessageHandler.java b/web/gui/src/main/java/org/onosproject/ui/impl/TopologyViewMessageHandler.java
index c27772f..13dde08 100644
--- a/web/gui/src/main/java/org/onosproject/ui/impl/TopologyViewMessageHandler.java
+++ b/web/gui/src/main/java/org/onosproject/ui/impl/TopologyViewMessageHandler.java
@@ -311,9 +311,11 @@
         HostId two = hostId(string(payload, "two"));
 
         HostToHostIntent intent =
-                new HostToHostIntent(appId, one, two,
-                                     DefaultTrafficSelector.emptySelector(),
-                                     DefaultTrafficTreatment.emptyTreatment());
+                HostToHostIntent.builder()
+                        .appId(appId)
+                        .one(one)
+                        .two(two)
+                        .build();
 
         intentService.submit(intent);
         startMonitoringIntent(event, intent);
@@ -336,8 +338,13 @@
         TrafficTreatment treatment = DefaultTrafficTreatment.emptyTreatment();
 
         MultiPointToSinglePointIntent intent =
-                new MultiPointToSinglePointIntent(appId, selector, treatment,
-                                                  ingressPoints, dstHost.location());
+                MultiPointToSinglePointIntent.builder()
+                        .appId(appId)
+                        .selector(selector)
+                        .treatment(treatment)
+                        .ingressPoints(ingressPoints)
+                        .egressPoint(dstHost.location())
+                        .build();
 
         intentService.submit(intent);
         startMonitoringIntent(event, intent);