Checkstyle and pmd fixes for new MatchAction service

Change-Id: I13efd4c7a29e19b782c126132d151ac377db3a4c
diff --git a/src/main/java/net/onrc/onos/core/matchaction/web/MatchActionResource.java b/src/main/java/net/onrc/onos/core/matchaction/web/MatchActionResource.java
index 20e68d3..ca3f95e 100644
--- a/src/main/java/net/onrc/onos/core/matchaction/web/MatchActionResource.java
+++ b/src/main/java/net/onrc/onos/core/matchaction/web/MatchActionResource.java
@@ -22,7 +22,7 @@
  */
 public class MatchActionResource extends ServerResource {
 
-    CustomSerializerHelper matchActionSerializers;
+    private final CustomSerializerHelper matchActionSerializers;
 
     /**
      * Constructs a MatchActionResource.