Introduce library property is_stubs_module

is_stubs_module property signifies whether the module compiles stubs or
not. The information is propagated to the reverse dependencies of the
java_library/java_sdk_library modules via JavaInfoProvider as
StubsLinkType, a ternary state that provides information about whether
the provided jars are compilation of stubs or implementation, or
unknown.

When java_sdk_library sets StubsLinkType, its state is Unknown as the
decision of providing stubs vs implementation jar differs by the reverse
dependency.

Note that this CL does NOT propagate the property up to its reverse
dependencies. This will be done in follow up CLs.

Test: m nothing
Bug: 310504781
Merged-In: Ic81488dbd1c9af1b5d31a33e5e9441d9f1416dbe
Change-Id: Ic81488dbd1c9af1b5d31a33e5e9441d9f1416dbe
diff --git a/java/java.go b/java/java.go
index d7d271c..1a266b8 100644
--- a/java/java.go
+++ b/java/java.go
@@ -87,6 +87,14 @@
 	android.RegisterSdkMemberType(javaTestSdkMemberType)
 }
 
+type StubsLinkType int
+
+const (
+	Unknown StubsLinkType = iota
+	Stubs
+	Implementation
+)
+
 var (
 	// Supports adding java header libraries to module_exports and sdk.
 	javaHeaderLibsSdkMemberType = &librarySdkMemberType{
@@ -296,6 +304,11 @@
 	// JacocoReportClassesFile is the path to a jar containing uninstrumented classes that will be
 	// instrumented by jacoco.
 	JacocoReportClassesFile android.Path
+
+	// StubsLinkType provides information about whether the provided jars are stub jars or
+	// implementation jars. If the provider is set by java_sdk_library, the link type is "unknown"
+	// and selection between the stub jar vs implementation jar is deferred to SdkLibrary.sdkJars(...)
+	StubsLinkType StubsLinkType
 }
 
 var JavaInfoProvider = blueprint.NewProvider[JavaInfo]()
@@ -694,6 +707,17 @@
 	j.minSdkVersion = j.MinSdkVersion(ctx)
 	j.maxSdkVersion = j.MaxSdkVersion(ctx)
 
+	// SdkLibrary.GenerateAndroidBuildActions(ctx) sets the stubsLinkType to Unknown.
+	// If the stubsLinkType has already been set to Unknown, the stubsLinkType should
+	// not be overridden.
+	if j.stubsLinkType != Unknown {
+		if proptools.Bool(j.properties.Is_stubs_module) {
+			j.stubsLinkType = Stubs
+		} else {
+			j.stubsLinkType = Implementation
+		}
+	}
+
 	j.stem = proptools.StringDefault(j.overridableDeviceProperties.Stem, ctx.ModuleName())
 
 	proguardSpecInfo := j.collectProguardSpecInfo(ctx)
@@ -2018,6 +2042,7 @@
 		ImplementationAndResourcesJars: android.PathsIfNonNil(al.stubsJar),
 		ImplementationJars:             android.PathsIfNonNil(al.stubsJar),
 		AidlIncludeDirs:                android.Paths{},
+		StubsLinkType:                  Stubs,
 		// No aconfig libraries on api libraries
 	})
 }
@@ -2102,6 +2127,9 @@
 	// The name is the undecorated name of the java_sdk_library as it appears in the blueprint file
 	// (without any prebuilt_ prefix)
 	Created_by_java_sdk_library_name *string `blueprint:"mutated"`
+
+	// Property signifying whether the module provides stubs jar or not.
+	Is_stubs_module *bool
 }
 
 type Import struct {
@@ -2132,6 +2160,8 @@
 
 	sdkVersion    android.SdkSpec
 	minSdkVersion android.ApiLevel
+
+	stubsLinkType StubsLinkType
 }
 
 var _ PermittedPackagesForUpdatableBootJars = (*Import)(nil)
@@ -2226,6 +2256,12 @@
 	if ctx.Windows() {
 		j.HideFromMake()
 	}
+
+	if proptools.Bool(j.properties.Is_stubs_module) {
+		j.stubsLinkType = Stubs
+	} else {
+		j.stubsLinkType = Implementation
+	}
 }
 
 func (j *Import) GenerateAndroidBuildActions(ctx android.ModuleContext) {
@@ -2359,6 +2395,7 @@
 		ImplementationAndResourcesJars: android.PathsIfNonNil(j.combinedClasspathFile),
 		ImplementationJars:             android.PathsIfNonNil(j.combinedClasspathFile),
 		AidlIncludeDirs:                j.exportAidlIncludeDirs,
+		StubsLinkType:                  j.stubsLinkType,
 		// TODO(b/289117800): LOCAL_ACONFIG_FILES for prebuilts
 	})
 }