Share constants for droidstubs btw Soong & Bazel

Test: m bp2build && verify constants
Change-Id: I04865414fb627672821b10d8bcc736379dc3da86
diff --git a/java/config/Android.bp b/java/config/Android.bp
index 194e2c6..bfe83ab 100644
--- a/java/config/Android.bp
+++ b/java/config/Android.bp
@@ -12,6 +12,7 @@
     ],
     srcs: [
         "config.go",
+        "droidstubs.go",
         "error_prone.go",
         "kotlin.go",
         "makevars.go",
diff --git a/java/config/droidstubs.go b/java/config/droidstubs.go
new file mode 100644
index 0000000..59cee1d
--- /dev/null
+++ b/java/config/droidstubs.go
@@ -0,0 +1,85 @@
+// Copyright 2023 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import "strings"
+
+var (
+	metalavaFlags = []string{
+		"--color",
+		"--quiet",
+		"--format=v2",
+		"--repeat-errors-max 10",
+		"--hide UnresolvedImport",
+		"--hide InvalidNullabilityOverride",
+		// b/223382732
+		"--hide ChangedDefault",
+
+		// Force metalava to ignore classes on the classpath when an API file contains missing classes.
+		// See b/285140653 for more information.
+		"--api-class-resolution api",
+
+		// Force metalava to sort overloaded methods by their order in the source code.
+		// See b/285312164 for more information.
+		// And add concrete overrides of abstract methods, see b/299366704 for more
+		// information.
+		"--format-defaults overloaded-method-order=source,add-additional-overrides=yes",
+	}
+
+	MetalavaFlags = strings.Join(metalavaFlags, " ")
+
+	metalavaAnnotationsFlags = []string{
+		"--include-annotations",
+		"--exclude-annotation androidx.annotation.RequiresApi",
+	}
+
+	MetalavaAnnotationsFlags = strings.Join(metalavaAnnotationsFlags, " ")
+
+	metalavaAnnotationsWarningsFlags = []string{
+		// TODO(tnorbye): find owners to fix these warnings when annotation was enabled.
+		"--hide HiddenTypedefConstant",
+		"--hide SuperfluousPrefix",
+		"--hide AnnotationExtraction",
+		// b/222738070
+		"--hide BannedThrow",
+		// b/223382732
+		"--hide ChangedDefault",
+	}
+
+	MetalavaAnnotationsWarningsFlags = strings.Join(metalavaAnnotationsWarningsFlags, " ")
+
+	metalavaHideFlaggedApis = []string{
+		"--hide-annotation",
+		"android.annotation.FlaggedApi",
+	}
+
+	MetalavaHideFlaggedApis = strings.Join(metalavaHideFlaggedApis, " ")
+)
+
+const (
+	MetalavaAddOpens = "-J--add-opens=java.base/java.util=ALL-UNNAMED"
+)
+
+func init() {
+	exportedVars.ExportStringList("MetalavaFlags", metalavaFlags)
+
+	exportedVars.ExportString("MetalavaAddOpens", MetalavaAddOpens)
+
+	exportedVars.ExportStringList("MetalavaHideFlaggedApis", metalavaHideFlaggedApis)
+
+	exportedVars.ExportStringListStaticVariable("MetalavaAnnotationsFlags", metalavaAnnotationsFlags)
+
+	exportedVars.ExportStringListStaticVariable("MetalavaAnnotationWarningsFlags", metalavaAnnotationsWarningsFlags)
+}
diff --git a/java/droidstubs.go b/java/droidstubs.go
index 7cb4743..8039d05 100644
--- a/java/droidstubs.go
+++ b/java/droidstubs.go
@@ -322,9 +322,7 @@
 
 func (d *Droidstubs) annotationsFlags(ctx android.ModuleContext, cmd *android.RuleBuilderCommand) {
 	if Bool(d.properties.Annotations_enabled) {
-		cmd.Flag("--include-annotations")
-
-		cmd.FlagWithArg("--exclude-annotation ", "androidx.annotation.RequiresApi")
+		cmd.Flag(config.MetalavaAnnotationsFlags)
 
 		validatingNullability :=
 			strings.Contains(String(d.Javadoc.properties.Args), "--validate-nullability-from-merged-stubs") ||
@@ -352,14 +350,7 @@
 			d.mergeAnnoDirFlags(ctx, cmd)
 		}
 
-		// TODO(tnorbye): find owners to fix these warnings when annotation was enabled.
-		cmd.FlagWithArg("--hide ", "HiddenTypedefConstant").
-			FlagWithArg("--hide ", "SuperfluousPrefix").
-			FlagWithArg("--hide ", "AnnotationExtraction").
-			// b/222738070
-			FlagWithArg("--hide ", "BannedThrow").
-			// b/223382732
-			FlagWithArg("--hide ", "ChangedDefault")
+		cmd.Flag(config.MetalavaAnnotationsWarningsFlags)
 	}
 }
 
@@ -519,7 +510,7 @@
 
 	cmd.BuiltTool("metalava").ImplicitTool(ctx.Config().HostJavaToolPath(ctx, "metalava.jar")).
 		Flag(config.JavacVmFlags).
-		Flag("-J--add-opens=java.base/java.util=ALL-UNNAMED").
+		Flag(config.MetalavaAddOpens).
 		FlagWithArg("--java-source ", javaVersion.String()).
 		FlagWithRspFileInputList("@", android.PathForModuleOut(ctx, "metalava.rsp"), srcs).
 		FlagWithInput("@", srcJarList)
@@ -532,27 +523,9 @@
 		cmd.FlagWithInputList("--classpath ", combinedPaths, ":")
 	}
 
-	cmd.Flag("--color").
-		Flag("--quiet").
-		Flag("--format=v2").
-		FlagWithArg("--repeat-errors-max ", "10").
-		FlagWithArg("--hide ", "UnresolvedImport").
-		FlagWithArg("--hide ", "InvalidNullabilityOverride").
-		// b/223382732
-		FlagWithArg("--hide ", "ChangedDefault")
-
-	// Force metalava to ignore classes on the classpath when an API file contains missing classes.
-	// See b/285140653 for more information.
-	cmd.FlagWithArg("--api-class-resolution ", "api")
-
-	// Force metalava to sort overloaded methods by their order in the source code.
-	// See b/285312164 for more information.
-	// And add concrete overrides of abstract methods, see b/299366704 for more
-	// information.
-	cmd.FlagWithArg("--format-defaults ", "overloaded-method-order=source,add-additional-overrides=yes")
-
+	cmd.Flag(config.MetalavaFlags)
 	if ctx.DeviceConfig().HideFlaggedApis() {
-		cmd.FlagWithArg("--hide-annotation ", "android.annotation.FlaggedApi")
+		cmd.Flag(config.MetalavaHideFlaggedApis)
 	}
 
 	return cmd