Replace SortedStringKeys with SortedKeys

Now that we have generics.

Bug: 193460475
Test: presubmits
Change-Id: I1594fd8feb505175d5c09c03ef397e5ffd5b09cb
diff --git a/java/prebuilt_apis.go b/java/prebuilt_apis.go
index c6acd55..206d995 100644
--- a/java/prebuilt_apis.go
+++ b/java/prebuilt_apis.go
@@ -264,7 +264,7 @@
 	}
 
 	// Sort the keys in order to make build.ninja stable
-	for _, k := range android.SortedStringKeys(latest) {
+	for _, k := range android.SortedKeys(latest) {
 		info := latest[k]
 		name := PrebuiltApiModuleName(info.module, info.scope, "latest")
 		createApiModule(mctx, name, info.path)
@@ -284,7 +284,7 @@
 		}
 	}
 	// Create empty incompatibilities files for remaining modules
-	for _, k := range android.SortedStringKeys(latest) {
+	for _, k := range android.SortedKeys(latest) {
 		if _, ok := incompatibilities[k]; !ok {
 			createEmptyFile(mctx, PrebuiltApiModuleName(latest[k].module+"-incompatibilities", latest[k].scope, "latest"))
 		}