Fix instantiation of config.bazelForceEnabledModules

Currently, uninstantiated, the field will be set to [""]
instead of an empty slice.

Test: m nothing --ensure-allowlist-integrity
Test: m nothing --ensure-allowlist-integrity
--bazel-force-enabled-modules=com.google.android.neuralnetworks (this
fails, as expected)

Change-Id: Ib4cd26f0cb0d40714b8c3f263ee2d22093ee15ef
diff --git a/android/config.go b/android/config.go
index 5265374..9e94e05 100644
--- a/android/config.go
+++ b/android/config.go
@@ -606,7 +606,7 @@
 	setBazelMode(cmdArgs.BazelMode, "--bazel-mode", BazelProdMode)
 	setBazelMode(cmdArgs.BazelModeStaging, "--bazel-mode-staging", BazelStagingMode)
 
-	for _, module := range strings.Split(cmdArgs.BazelForceEnabledModules, ",") {
+	for _, module := range getForceEnabledModulesFromFlag(cmdArgs.BazelForceEnabledModules) {
 		config.bazelForceEnabledModules[module] = struct{}{}
 	}
 	config.BazelContext, err = NewBazelContext(config)
@@ -615,6 +615,13 @@
 	return Config{config}, err
 }
 
+func getForceEnabledModulesFromFlag(forceEnabledFlag string) []string {
+	if forceEnabledFlag == "" {
+		return []string{}
+	}
+	return strings.Split(forceEnabledFlag, ",")
+}
+
 // mockFileSystem replaces all reads with accesses to the provided map of
 // filenames to contents stored as a byte slice.
 func (c *config) mockFileSystem(bp string, fs map[string][]byte) {
diff --git a/cmd/soong_build/main.go b/cmd/soong_build/main.go
index f347b8f..c22fd80 100644
--- a/cmd/soong_build/main.go
+++ b/cmd/soong_build/main.go
@@ -307,10 +307,6 @@
 // This indicates the allowlisting of this variant had no effect.
 // TODO(b/280457637): Return true for nonexistent modules.
 func isAllowlistMisconfiguredForModule(module string, mixedBuildsEnabled map[string]struct{}, mixedBuildsDisabled map[string]struct{}) bool {
-	//TODO(dacek): Why does this occur in the allowlists?
-	if module == "" {
-		return false
-	}
 	_, enabled := mixedBuildsEnabled[module]
 
 	if enabled {