Simplify ConnectPoint#toString format

for ease of reading logs.

Change-Id: I981cf877eb53f64e77fdef48bca30625942bc8f2
diff --git a/core/api/src/test/java/org/onosproject/net/LinkKeyTest.java b/core/api/src/test/java/org/onosproject/net/LinkKeyTest.java
index 34a486e..0b036be 100644
--- a/core/api/src/test/java/org/onosproject/net/LinkKeyTest.java
+++ b/core/api/src/test/java/org/onosproject/net/LinkKeyTest.java
@@ -123,7 +123,7 @@
         LinkKey k1 = LinkKey.linkKey(SRC1, DST1);
         String k1String = k1.toString();
         assertThat(k1String, allOf(containsString("LinkKey{"),
-                                   containsString("src=ConnectPoint{elementId=1, portNumber=1}"),
-                                   containsString("dst=ConnectPoint{elementId=2, portNumber=1}")));
+                                   containsString("src=1/1"),
+                                   containsString("dst=2/1}")));
     }
 }