sdk_version: "module_current" is supported

module_* is a new API surface for OS modules (e.g. APEXes). It has
slightly bigger API surface than the system_* SDK. Specifically, APIs
with @SystemApi(client=MODULE_LIBRARIES) are added there.

Bug: 146757305
Test: m

Change-Id: I8980e50c0e3a4cd843048e0de1f638e854384f46

java/java.go

@@ -757,9 +757,12 @@ func checkProducesJars(ctx android.ModuleContext, dep android.SourceFileProducer
 type linkType int
 
 const (
+	// TODO(jiyong) rename these for better readability. Make the allowed
+	// and disallowed link types explicit
 	javaCore linkType = iota
 	javaSdk
 	javaSystem
+	javaModule
 	javaPlatform
 )
 
@@ -789,6 +792,10 @@ func (m *Module) getLinkType(name string) (ret linkType, stubs bool) {
 		return javaSdk, true
 	case ver.kind == sdkPublic:
 		return javaSdk, false
+	case name == "android_module_lib_stubs_current":
+		return javaModule, true
+	case ver.kind == sdkModule:
+		return javaModule, false
 	case ver.kind == sdkPrivate || ver.kind == sdkNone || ver.kind == sdkCorePlatform:
 		return javaPlatform, false
 	case !ver.valid():
@@ -824,11 +831,17 @@ func checkLinkType(ctx android.ModuleContext, from *Module, to linkTypeContext,
 		}
 		break
 	case javaSystem:
-		if otherLinkType == javaPlatform {
+		if otherLinkType == javaPlatform || otherLinkType == javaModule {
 			ctx.ModuleErrorf("compiles against system API, but dependency %q is compiling against private API."+commonMessage,
 				ctx.OtherModuleName(to))
 		}
 		break
+	case javaModule:
+		if otherLinkType == javaPlatform {
+			ctx.ModuleErrorf("compiles against module API, but dependency %q is compiling against private API."+commonMessage,
+				ctx.OtherModuleName(to))
+		}
+		break
 	case javaPlatform:
 		// no restriction on link-type
 		break