Assert android.ApexModule interface for types having ApexModuleBase

Bug: 173472337
Test: m nothing
Change-Id: Idf1c6cb9fff6c18e34c4636e38a662ba4ff7d538
diff --git a/java/app.go b/java/app.go
index e6d9550..c0ac9c2 100755
--- a/java/app.go
+++ b/java/app.go
@@ -1653,6 +1653,9 @@
 	return sdkSpecFrom("")
 }
 
+var _ android.ApexModule = (*AndroidAppImport)(nil)
+
+// Implements android.ApexModule
 func (j *AndroidAppImport) ShouldSupportSdkVersion(ctx android.BaseModuleContext,
 	sdkVersion android.ApiLevel) error {
 	// Do not check for prebuilts against the min_sdk_version of enclosing APEX