Allow java_sdk_library in an APEX to have higher min_sdk_version.

Inidividual boot or system server jars may have higher min_sdk_version
than the contianing apex, since the runtime respects the values of
min/max_sdk_version; e.g. runtime would not load a boot jar with
higher min_sdk_version. This allows shipping new boot jars via apexes
that target older platforms.

Bug: 190818041
Test: presubmit
Change-Id: I08ec0b4463a17bc8265b948fe09da55eb4e52ac3
diff --git a/java/sdk_library.go b/java/sdk_library.go
index fec0000..52ab06e 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -1129,6 +1129,8 @@
 	return generatedScopes
 }
 
+var _ android.ModuleWithMinSdkVersionCheck = (*SdkLibrary)(nil)
+
 func (module *SdkLibrary) CheckMinSdkVersion(ctx android.ModuleContext) {
 	android.CheckMinSdkVersion(ctx, module.MinSdkVersion(ctx).ApiLevel, func(c android.ModuleContext, do android.PayloadDepsCallback) {
 		ctx.WalkDeps(func(child android.Module, parent android.Module) bool {