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

java/sdk_library.go

@@ -1572,6 +1572,8 @@ func (module *SdkLibrary) GenerateAndroidBuildActions(ctx android.ModuleContext)
 
 	// Only build an implementation library if required.
 	if module.requiresRuntimeImplementationLibrary() {
+		// stubsLinkType must be set before calling Library.GenerateAndroidBuildActions
+		module.Library.stubsLinkType = Unknown
 		module.Library.GenerateAndroidBuildActions(ctx)
 	}
 
@@ -1797,6 +1799,7 @@ type libraryProperties struct {
 		Dir     *string
 		Tag     *string
 	}
+	Is_stubs_module *bool
 }
 
 func (module *SdkLibrary) stubsLibraryProps(mctx android.DefaultableHookContext, apiScope *apiScope) libraryProperties {
@@ -1821,6 +1824,7 @@ func (module *SdkLibrary) stubsLibraryProps(mctx android.DefaultableHookContext,
 	// We compile the stubs for 1.8 in line with the main android.jar stubs, and potential
 	// interop with older developer tools that don't support 1.9.
 	props.Java_version = proptools.StringPtr("1.8")
+	props.Is_stubs_module = proptools.BoolPtr(true)
 
 	return props
 }
@@ -2709,6 +2713,7 @@ func (module *SdkLibraryImport) createJavaImportForStubs(mctx android.Defaultabl
 		Libs                             []string
 		Jars                             []string
 		Compile_dex                      *bool
+		Is_stubs_module                  *bool
 
 		android.UserSuppliedPrebuiltProperties
 	}{}
@@ -2730,6 +2735,7 @@ func (module *SdkLibraryImport) createJavaImportForStubs(mctx android.Defaultabl
 		compileDex = proptools.BoolPtr(true)
 	}
 	props.Compile_dex = compileDex
+	props.Is_stubs_module = proptools.BoolPtr(true)
 
 	mctx.CreateModule(ImportFactory, &props, module.sdkComponentPropertiesForChildLibrary())
 }