diff --git a/java_gen/templates/_imports.java b/java_gen/templates/_imports.java
index 669db00..ef683e6 100644
--- a/java_gen/templates/_imports.java
+++ b/java_gen/templates/_imports.java
@@ -1,6 +1,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.Set;
 import java.util.Map;
 import org.projectfloodlight.openflow.protocol.*;
 import org.projectfloodlight.openflow.protocol.action.*;