diff --git a/apex/apex.go b/apex/apex.go
index 16027e1..ec87f5b 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -561,7 +561,6 @@
 		"libnativebridge_lazy",
 		"libnativeloader_lazy",
 		"libnativewindow_headers",
-		"libopus",
 		"libpdx_headers",
 		"libprocessgroup",
 		"libprocessgroup_headers",
@@ -806,12 +805,6 @@
 }
 
 func init() {
-	android.AddNeverAllowRules(android.NeverAllow().
-		ModuleType("apex").
-		With("updatable", "true").
-		With("min_sdk_version", "").
-		Because("All updatable apexes should set min_sdk_version."))
-
 	android.RegisterModuleType("apex", BundleFactory)
 	android.RegisterModuleType("apex_test", testApexBundleFactory)
 	android.RegisterModuleType("apex_vndk", vndkApexBundleFactory)
@@ -1172,8 +1165,10 @@
 	IsCoverageVariant bool `blueprint:"mutated"`
 
 	// Whether this APEX is considered updatable or not. When set to true, this will enforce additional
-	// rules for making sure that the APEX is truely updatable. This will also disable the size optimizations
-	// like symlinking to the system libs. Default is false.
+	// rules for making sure that the APEX is truly updatable.
+	// - To be updatable, min_sdk_version should be set as well
+	// This will also disable the size optimizations like symlinking to the system libs.
+	// Default is false.
 	Updatable *bool
 
 	// The minimum SDK version that this apex must be compatible with.
@@ -1946,6 +1941,14 @@
 	})
 }
 
+func (a *apexBundle) checkUpdatable(ctx android.ModuleContext) {
+	if proptools.Bool(a.properties.Updatable) {
+		if String(a.properties.Min_sdk_version) == "" {
+			ctx.PropertyErrorf("updatable", "updatable APEXes should set min_sdk_version as well")
+		}
+	}
+}
+
 // Collects the list of module names that directly or indirectly contributes to the payload of this APEX
 func (a *apexBundle) collectDepsInfo(ctx android.ModuleContext) {
 	a.depInfos = make(map[string]depInfo)
@@ -2011,6 +2014,7 @@
 	}
 
 	a.checkApexAvailability(ctx)
+	a.checkUpdatable(ctx)
 
 	a.collectDepsInfo(ctx)
 
diff --git a/apex/apex_test.go b/apex/apex_test.go
index 44cc527..91ad6e8 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -4040,6 +4040,7 @@
 			native_shared_libs: ["mylib"],
 			java_libs: ["myjar"],
 			updatable: true,
+			min_sdk_version: "current",
 		}
 
 		apex_key {
@@ -4265,6 +4266,22 @@
 	}
 }
 
+func TestUpdatable_should_set_min_sdk_version(t *testing.T) {
+	testApexError(t, `"myapex" .*: updatable: updatable APEXes should set min_sdk_version`, `
+		apex {
+			name: "myapex",
+			key: "myapex.key",
+			updatable: true,
+		}
+
+		apex_key {
+			name: "myapex.key",
+			public_key: "testkey.avbpubkey",
+			private_key: "testkey.pem",
+		}
+	`)
+}
+
 func TestNoUpdatableJarsInBootImage(t *testing.T) {
 	bp := `
 		java_library {
diff --git a/java/app_test.go b/java/app_test.go
index b1c8b63..39460dc 100644
--- a/java/app_test.go
+++ b/java/app_test.go
@@ -2540,3 +2540,62 @@
 		t.Errorf("Unexpected LOCAL_OVERRIDES_PACKAGES value: %v, expected: %v", overrides, expectedOverrides)
 	}
 }
+
+func TestRuntimeResourceOverlay_JavaDefaults(t *testing.T) {
+	ctx, config := testJava(t, `
+		java_defaults {
+			name: "rro_defaults",
+			theme: "default_theme",
+			product_specific: true,
+			aaptflags: ["--keep-raw-values"],
+		}
+
+		runtime_resource_overlay {
+			name: "foo_with_defaults",
+			defaults: ["rro_defaults"],
+		}
+
+		runtime_resource_overlay {
+			name: "foo_barebones",
+		}
+		`)
+
+	//
+	// RRO module with defaults
+	//
+	m := ctx.ModuleForTests("foo_with_defaults", "android_common")
+
+	// Check AAPT2 link flags.
+	aapt2Flags := strings.Split(m.Output("package-res.apk").Args["flags"], " ")
+	expectedFlags := []string{"--keep-raw-values", "--no-resource-deduping", "--no-resource-removal"}
+	absentFlags := android.RemoveListFromList(expectedFlags, aapt2Flags)
+	if len(absentFlags) > 0 {
+		t.Errorf("expected values, %q are missing in aapt2 link flags, %q", absentFlags, aapt2Flags)
+	}
+
+	// Check device location.
+	path := android.AndroidMkEntriesForTest(t, config, "", m.Module())[0].EntryMap["LOCAL_MODULE_PATH"]
+	expectedPath := []string{"/tmp/target/product/test_device/product/overlay/default_theme"}
+	if !reflect.DeepEqual(path, expectedPath) {
+		t.Errorf("Unexpected LOCAL_MODULE_PATH value: %q, expected: %q", path, expectedPath)
+	}
+
+	//
+	// RRO module without defaults
+	//
+	m = ctx.ModuleForTests("foo_barebones", "android_common")
+
+	// Check AAPT2 link flags.
+	aapt2Flags = strings.Split(m.Output("package-res.apk").Args["flags"], " ")
+	unexpectedFlags := "--keep-raw-values"
+	if inList(unexpectedFlags, aapt2Flags) {
+		t.Errorf("unexpected value, %q is present in aapt2 link flags, %q", unexpectedFlags, aapt2Flags)
+	}
+
+	// Check device location.
+	path = android.AndroidMkEntriesForTest(t, config, "", m.Module())[0].EntryMap["LOCAL_MODULE_PATH"]
+	expectedPath = []string{"/tmp/target/product/test_device/system/overlay"}
+	if !reflect.DeepEqual(path, expectedPath) {
+		t.Errorf("Unexpected LOCAL_MODULE_PATH value: %v, expected: %v", path, expectedPath)
+	}
+}
diff --git a/java/droiddoc.go b/java/droiddoc.go
index 8f08f1f..7ac71a4 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -1524,40 +1524,35 @@
 		apiFile := android.PathForModuleSrc(ctx, String(d.properties.Check_api.Current.Api_file))
 		removedApiFile := android.PathForModuleSrc(ctx, String(d.properties.Check_api.Current.Removed_api_file))
 		baselineFile := android.OptionalPathForModuleSrc(ctx, d.properties.Check_api.Current.Baseline_file)
-		updatedBaselineOutput := android.PathForModuleOut(ctx, "current_baseline.txt")
+
+		if baselineFile.Valid() {
+			ctx.PropertyErrorf("current API check can't have a baseline file. (module %s)", ctx.ModuleName())
+		}
 
 		d.checkCurrentApiTimestamp = android.PathForModuleOut(ctx, "check_current_api.timestamp")
 
 		rule := android.NewRuleBuilder()
 
+		// Diff command line.
+		// -F matches the closest "opening" line, such as "package xxx{"
+		// and "  public class Yyy {".
+		diff := `diff -u -F '{ *$'`
+
 		rule.Command().Text("( true")
+		rule.Command().
+			Text(diff).
+			Input(apiFile).Input(d.apiFile)
 
-		srcJarDir := android.PathForModuleOut(ctx, "current-apicheck", "srcjars")
-		srcJarList := zipSyncCmd(ctx, rule, srcJarDir, d.Javadoc.srcJars)
-
-		cmd := metalavaCmd(ctx, rule, javaVersion, d.Javadoc.srcFiles, srcJarList,
-			deps.bootClasspath, deps.classpath, d.Javadoc.sourcepaths)
-
-		cmd.Flag(d.Javadoc.args).Implicits(d.Javadoc.argFiles).
-			FlagWithInput("--check-compatibility:api:current ", apiFile).
-			FlagWithInput("--check-compatibility:removed:current ", removedApiFile)
-
-		d.inclusionAnnotationsFlags(ctx, cmd)
-		d.mergeAnnoDirFlags(ctx, cmd)
-
-		if baselineFile.Valid() {
-			cmd.FlagWithInput("--baseline ", baselineFile.Path())
-			cmd.FlagWithOutput("--update-baseline ", updatedBaselineOutput)
-		}
-
-		zipSyncCleanupCmd(rule, srcJarDir)
+		rule.Command().
+			Text(diff).
+			Input(removedApiFile).Input(d.removedApiFile)
 
 		msg := fmt.Sprintf(`\n******************************\n`+
 			`You have tried to change the API from what has been previously approved.\n\n`+
 			`To make these errors go away, you have two choices:\n`+
-			`   1. You can add '@hide' javadoc comments to the methods, etc. listed in the\n`+
-			`      errors above.\n\n`+
-			`   2. You can update current.txt by executing the following command:\n`+
+			`   1. You can add '@hide' javadoc comments (and remove @SystemApi/@TestApi/etc)\n`+
+			`      to the new methods, etc. shown in the above diff.\n\n`+
+			`   2. You can update current.txt and/or removed.txt by executing the following command:\n`+
 			`         make %s-update-current-api\n\n`+
 			`      To submit the revised current.txt to the main Android repository,\n`+
 			`      you will need approval.\n`+
@@ -1570,7 +1565,7 @@
 			Text("; exit 38").
 			Text(")")
 
-		rule.Build(pctx, ctx, "metalavaCurrentApiCheck", "metalava check current API")
+		rule.Build(pctx, ctx, "metalavaCurrentApiCheck", "check current API")
 
 		d.updateCurrentApiTimestamp = android.PathForModuleOut(ctx, "update_current_api.timestamp")
 
diff --git a/java/java.go b/java/java.go
index 1c2e22a..5d77807 100644
--- a/java/java.go
+++ b/java/java.go
@@ -2745,6 +2745,7 @@
 		&sdkLibraryProperties{},
 		&DexImportProperties{},
 		&android.ApexProperties{},
+		&RuntimeResourceOverlayProperties{},
 	)
 
 	android.InitDefaultsModule(module)