diff --git a/java/bootclasspath.go b/java/bootclasspath.go
index eddcc83..ccb69a0 100644
--- a/java/bootclasspath.go
+++ b/java/bootclasspath.go
@@ -144,6 +144,8 @@
 
 // ApexVariantReference specifies a particular apex variant of a module.
 type ApexVariantReference struct {
+	android.BpPrintableBase
+
 	// The name of the module apex variant, i.e. the apex containing the module variant.
 	//
 	// If this is not specified then it defaults to "platform" which will cause a dependency to be