Avoid unnecessary empty list instantiation

Change-Id: I128485be4e0d7d3400741855e4519f441cfb34c5
diff --git a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer10.java b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer10.java
index f9ad345..47b5a30 100644
--- a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer10.java
+++ b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer10.java
@@ -142,7 +142,7 @@
             switch (i.type()) {
             case DROP:
                 log.warn("Saw drop action; assigning drop action");
-                return new LinkedList<>();
+                return Collections.emptyList();
             case L2MODIFICATION:
                 acts.add(buildL2Modification(i));
                 break;
diff --git a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java
index 3ba155f..698c77c 100644
--- a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java
+++ b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java
@@ -194,7 +194,7 @@
         for (Instruction i : treatments) {
             switch (i.type()) {
                 case DROP:
-                    return new LinkedList<>();
+                    return Collections.emptyList();
                 case L0MODIFICATION:
                     actions.add(buildL0Modification(i));
                     break;