Remove dependency on LinkResourceService from Constraint

Change-Id: Ib9c488331b22eef6769a767c6186ef7d2e8b1501
diff --git a/core/api/src/main/java/org/onosproject/net/intent/constraint/ObstacleConstraint.java b/core/api/src/main/java/org/onosproject/net/intent/constraint/ObstacleConstraint.java
index ca4f3fd..7487512 100644
--- a/core/api/src/main/java/org/onosproject/net/intent/constraint/ObstacleConstraint.java
+++ b/core/api/src/main/java/org/onosproject/net/intent/constraint/ObstacleConstraint.java
@@ -20,7 +20,7 @@
 import com.google.common.collect.ImmutableSet;
 import org.onosproject.net.DeviceId;
 import org.onosproject.net.Link;
-import org.onosproject.net.resource.link.LinkResourceService;
+import org.onosproject.net.intent.ResourceContext;
 
 import java.util.Collections;
 import java.util.Objects;
@@ -56,8 +56,14 @@
         return obstacles;
     }
 
+    // doesn't use LinkResourceService
     @Override
-    public boolean isValid(Link link, LinkResourceService resourceService) {
+    public boolean isValid(Link link, ResourceContext context) {
+        // explicitly call a method not depending on LinkResourceService
+        return isValid(link);
+    }
+
+    private boolean isValid(Link link) {
         DeviceId src = link.src().deviceId();
         DeviceId dst = link.dst().deviceId();