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/core/net/src/test/java/org/onosproject/net/intent/impl/compiler/HostToHostIntentCompilerTest.java b/core/net/src/test/java/org/onosproject/net/intent/impl/compiler/HostToHostIntentCompilerTest.java
index b154d22..be9ab66 100644
--- a/core/net/src/test/java/org/onosproject/net/intent/impl/compiler/HostToHostIntentCompilerTest.java
+++ b/core/net/src/test/java/org/onosproject/net/intent/impl/compiler/HostToHostIntentCompilerTest.java
@@ -90,8 +90,13 @@
      * @return HostToHostIntent for the two hosts
      */
     private HostToHostIntent makeIntent(String oneIdString, String twoIdString) {
-        return new HostToHostIntent(APPID, hid(oneIdString), hid(twoIdString),
-                                    selector, treatment);
+        return HostToHostIntent.builder()
+                .appId(APPID)
+                .one(hid(oneIdString))
+                .two(hid(twoIdString))
+                .selector(selector)
+                .treatment(treatment)
+                .build();
     }
 
     /**