java_sdk_library: Add annotations_enabled property

Passes it through to droidstubs.

Bug: 155164730
Test: m droid
Change-Id: I8b23a959ce33716dfc4572488a1fd3f6bab73a17
Merged-In: I8b23a959ce33716dfc4572488a1fd3f6bab73a17
(cherry picked from commit 2ce1e81b3e67a069afa80a2dd15d4ac6b3ce3655)
diff --git a/java/sdk_library.go b/java/sdk_library.go
index a5db56c..30478a1 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -419,6 +419,9 @@
 	//  $(location <label>): the path to the droiddoc_option_files with name <label>
 	Droiddoc_options []string
 
+	// is set to true, Metalava will allow framework SDK to contain annotations.
+	Annotations_enabled *bool
+
 	// a list of top-level directories containing files to merge qualifier annotations
 	// (i.e. those intended to be included in the stubs written) from.
 	Merge_annotations_dirs []string
@@ -1159,6 +1162,11 @@
 	props.Patch_module = module.properties.Patch_module
 	props.Installable = proptools.BoolPtr(false)
 	props.Libs = module.sdkLibraryProperties.Stub_only_libs
+	// The stub-annotations library contains special versions of the annotations
+	// with CLASS retention policy, so that they're kept.
+	if proptools.Bool(module.sdkLibraryProperties.Annotations_enabled) {
+		props.Libs = append(props.Libs, "stub-annotations")
+	}
 	props.Openjdk9.Srcs = module.properties.Openjdk9.Srcs
 	props.Openjdk9.Javacflags = module.properties.Openjdk9.Javacflags
 	// We compile the stubs for 1.8 in line with the main android.jar stubs, and potential
@@ -1193,6 +1201,7 @@
 		Arg_files                        []string
 		Args                             *string
 		Java_version                     *string
+		Annotations_enabled              *bool
 		Merge_annotations_dirs           []string
 		Merge_inclusion_annotations_dirs []string
 		Generate_stubs                   *bool
@@ -1243,6 +1252,7 @@
 	props.Aidl.Local_include_dirs = module.deviceProperties.Aidl.Local_include_dirs
 	props.Java_version = module.properties.Java_version
 
+	props.Annotations_enabled = module.sdkLibraryProperties.Annotations_enabled
 	props.Merge_annotations_dirs = module.sdkLibraryProperties.Merge_annotations_dirs
 	props.Merge_inclusion_annotations_dirs = module.sdkLibraryProperties.Merge_inclusion_annotations_dirs