Add previous_api property to java_api_library module

`Previous_api` is used to migrate nullness information in metalava (i.e.
convert @Nullable and @NonNull to @RecentlyNullable and @RecentlyNonNull
for some methods). The input is required to generate loosely equivalent
from-text stubs.

Test: m && compare nullness annotations between from-source stubs and from-text stubs
Bug: 293962901
Change-Id: Ic7a0868415fdb2c65d0d472e527fe73280b7651d

java/java.go

@@ -1683,6 +1683,9 @@ type JavaApiLibraryProperties struct {
 	// extracting the compiled class files provided by the
 	// full_api_surface_stub module.
 	Full_api_surface_stub *string
+
+	// Version of previously released API file for compatibility check.
+	Previous_api *string `android:"path"`
 }
 
 func ApiLibraryFactory() android.Module {
@@ -1890,6 +1893,12 @@ func (al *ApiLibrary) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 
 	al.stubsFlags(ctx, cmd, stubsDir)
 
+	migratingNullability := String(al.properties.Previous_api) != ""
+	if migratingNullability {
+		previousApi := android.PathForModuleSrc(ctx, String(al.properties.Previous_api))
+		cmd.FlagWithInput("--migrate-nullness ", previousApi)
+	}
+
 	al.stubsSrcJar = android.PathForModuleOut(ctx, "metalava", ctx.ModuleName()+"-"+"stubs.srcjar")
 	al.stubsJarWithoutStaticLibs = android.PathForModuleOut(ctx, "metalava", "stubs.jar")
 	al.stubsJar = android.PathForModuleOut(ctx, ctx.ModuleName(), fmt.Sprintf("%s.jar", ctx.ModuleName()))