Use apache commons Pair instead of javafx

It looks like javafx does not have Pair when using OpenJDK.

Change-Id: I3379dc87e0515185714b28ca0832a36b76b0772f
diff --git a/apps/segmentrouting/web/src/main/java/org/onosproject/segmentrouting/web/PseudowireCodec.java b/apps/segmentrouting/web/src/main/java/org/onosproject/segmentrouting/web/PseudowireCodec.java
index 755cb68..00d20a7 100644
--- a/apps/segmentrouting/web/src/main/java/org/onosproject/segmentrouting/web/PseudowireCodec.java
+++ b/apps/segmentrouting/web/src/main/java/org/onosproject/segmentrouting/web/PseudowireCodec.java
@@ -17,7 +17,7 @@
 
 import com.fasterxml.jackson.databind.node.ArrayNode;
 import com.fasterxml.jackson.databind.node.ObjectNode;
-import javafx.util.Pair;
+import org.apache.commons.lang3.tuple.Pair;
 import org.onlab.packet.MplsLabel;
 import org.onlab.packet.VlanId;
 import org.onosproject.codec.CodecContext;