diff --git a/java_gen/templates/_imports.java b/java_gen/templates/_imports.java
index dde3ac0..f84efbe 100644
--- a/java_gen/templates/_imports.java
+++ b/java_gen/templates/_imports.java
@@ -5,6 +5,8 @@
 import java.util.List;
 import java.util.Set;
 import java.util.Map;
+import javax.annotation.Nullable;
+import javax.annotation.Nonnull;
 import org.projectfloodlight.openflow.protocol.*;
 import org.projectfloodlight.openflow.protocol.action.*;
 import org.projectfloodlight.openflow.protocol.actionid.*;