Use label for module map name

PiperOrigin-RevId: 437022686
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
index 42a948e..f8f1962 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
@@ -292,7 +292,8 @@
   /** {@link CppModuleMap} for layering check and modules. */
   @StarlarkMethod(name = "internal_module_map", documented = false, structField = true)
   public CppModuleMap internalModuleMap() {
-    return new CppModuleMap(appendExtensionInGenfiles(".internal.cppmap"), getModuleName());
+    return new CppModuleMap(
+        appendExtensionInGenfiles(".internal.cppmap"), ruleContext.getLabel().toString());
   }
 
   /**