[CORD-2774] Support Dual-homing

Change-Id: I54d26e6dd0a76ba726afdf3b7160c46dcf6b79c5
(cherry picked from commit 57262b2076d5662f9d3390655cee105dac581b13)
diff --git a/apps/t3/src/main/java/org/onosproject/t3/api/TroubleshootService.java b/apps/t3/src/main/java/org/onosproject/t3/api/TroubleshootService.java
index 028df64..28ff728 100644
--- a/apps/t3/src/main/java/org/onosproject/t3/api/TroubleshootService.java
+++ b/apps/t3/src/main/java/org/onosproject/t3/api/TroubleshootService.java
@@ -22,6 +22,7 @@
 import org.onosproject.net.flow.TrafficSelector;
 
 import java.util.List;
+import java.util.Set;
 
 /**
  * API for troubleshooting services, providing static analysis of installed
@@ -45,7 +46,7 @@
      * @param type            the etherType of the traffic we want to trace.
      * @return a trace result
      */
-    StaticPacketTrace trace(HostId sourceHost, HostId destinationHost, EthType.EtherType type);
+    Set<StaticPacketTrace> trace(HostId sourceHost, HostId destinationHost, EthType.EtherType type);
 
     /**
      * Requests a static trace be performed for the given traffic selector