Prevent duplicated license_kinds

Bazel fails when there are duplicate license_kinds.

Bug: 260148018
Test: go test
Change-Id: I47a27d37d66be947e4a744cd04a3cdcc0b000de4
diff --git a/android/license.go b/android/license.go
index cde5e6e..ab8431a 100644
--- a/android/license.go
+++ b/android/license.go
@@ -15,10 +15,12 @@
 package android
 
 import (
-	"android/soong/bazel"
 	"fmt"
-	"github.com/google/blueprint"
 	"os"
+
+	"github.com/google/blueprint"
+
+	"android/soong/bazel"
 )
 
 type licenseKindDependencyTag struct {
@@ -101,6 +103,14 @@
 }
 
 func (m *licenseModule) DepsMutator(ctx BottomUpMutatorContext) {
+	for i, license := range m.properties.License_kinds {
+		for j := i + 1; j < len(m.properties.License_kinds); j++ {
+			if license == m.properties.License_kinds[j] {
+				ctx.ModuleErrorf("Duplicated license kind: %q", license)
+				break
+			}
+		}
+	}
 	ctx.AddVariationDependencies(nil, licenseKindTag, m.properties.License_kinds...)
 }
 
diff --git a/android/license_test.go b/android/license_test.go
index 7222cd7..89e7f06 100644
--- a/android/license_test.go
+++ b/android/license_test.go
@@ -90,6 +90,36 @@
 		},
 	},
 	{
+		name: "must not duplicate license_kind",
+		fs: map[string][]byte{
+			"top/Android.bp": []byte(`
+				license_kind {
+					name: "top_by_exception_only",
+					conditions: ["by_exception_only"],
+					visibility: ["//visibility:private"],
+				}
+
+				license_kind {
+					name: "top_by_exception_only_2",
+					conditions: ["by_exception_only"],
+					visibility: ["//visibility:private"],
+				}
+
+				license {
+					name: "top_proprietary",
+					license_kinds: [
+						"top_by_exception_only",
+						"top_by_exception_only_2",
+						"top_by_exception_only"
+					],
+					visibility: ["//visibility:public"],
+				}`),
+		},
+		expectedErrors: []string{
+			`top/Android.bp:14:5: module "top_proprietary": Duplicated license kind: "top_by_exception_only"`,
+		},
+	},
+	{
 		name: "license_kind module must exist",
 		fs: map[string][]byte{
 			"top/Android.bp": []byte(`