platform_bootclasspath: aggregate hidden API flag files from fragments

Aggregates hidden API flag files from the bootclasspath_fragments which
will allow the hidden API flag files in frameworks/base/boot/hiddenapi
to be modularized and moved to the appropriate repo.

Bug: 177892522
Test: verified that the out/soong/hiddenapi/... files are unchanged
      by this change
      also verified that changes to the fragment provided files do
      affect the monolithic files.
Change-Id: Ifce14c9ef24c58c7ab1085475d85b61cfbfefecd

java/platform_bootclasspath_test.go

@@ -15,6 +15,8 @@
 package java
 
 import (
+	"fmt"
+	"strings"
 	"testing"
 
 	"android/soong/android"
@@ -132,6 +134,96 @@ func TestPlatformBootclasspath(t *testing.T) {
 	})
 }
 
+func TestPlatformBootclasspath_Fragments(t *testing.T) {
+	result := android.GroupFixturePreparers(
+		prepareForTestWithPlatformBootclasspath,
+		android.FixtureWithRootAndroidBp(`
+			platform_bootclasspath {
+				name: "platform-bootclasspath",
+				fragments: [
+					{module:"bar-fragment"},
+				],
+				hidden_api: {
+					unsupported: [
+							"unsupported.txt",
+					],
+					removed: [
+							"removed.txt",
+					],
+					max_target_r_low_priority: [
+							"max-target-r-low-priority.txt",
+					],
+					max_target_q: [
+							"max-target-q.txt",
+					],
+					max_target_p: [
+							"max-target-p.txt",
+					],
+					max_target_o_low_priority: [
+							"max-target-o-low-priority.txt",
+					],
+					blocked: [
+							"blocked.txt",
+					],
+					unsupported_packages: [
+							"unsupported-packages.txt",
+					],
+				},
+			}
+
+			bootclasspath_fragment {
+				name: "bar-fragment",
+				contents: ["bar"],
+				hidden_api: {
+					unsupported: [
+							"bar-unsupported.txt",
+					],
+					removed: [
+							"bar-removed.txt",
+					],
+					max_target_r_low_priority: [
+							"bar-max-target-r-low-priority.txt",
+					],
+					max_target_q: [
+							"bar-max-target-q.txt",
+					],
+					max_target_p: [
+							"bar-max-target-p.txt",
+					],
+					max_target_o_low_priority: [
+							"bar-max-target-o-low-priority.txt",
+					],
+					blocked: [
+							"bar-blocked.txt",
+					],
+					unsupported_packages: [
+							"bar-unsupported-packages.txt",
+					],
+				},
+			}
+
+			java_library {
+				name: "bar",
+				srcs: ["a.java"],
+				system_modules: "none",
+				sdk_version: "none",
+				compile_dex: true,
+			}
+		`),
+	).RunTest(t)
+
+	pbcp := result.Module("platform-bootclasspath", "android_common")
+	info := result.ModuleProvider(pbcp, hiddenAPIFlagFileInfoProvider).(hiddenAPIFlagFileInfo)
+
+	for _, category := range hiddenAPIFlagFileCategories {
+		name := category.propertyName
+		message := fmt.Sprintf("category %s", name)
+		filename := strings.ReplaceAll(name, "_", "-")
+		expected := []string{fmt.Sprintf("%s.txt", filename), fmt.Sprintf("bar-%s.txt", filename)}
+		android.AssertPathsRelativeToTopEquals(t, message, expected, info.categoryToPaths[category])
+	}
+}
+
 func TestPlatformBootclasspathVariant(t *testing.T) {
 	result := android.GroupFixturePreparers(
 		prepareForTestWithPlatformBootclasspath,