Add a way to selectively enable TurboModules

Summary:
Added a flag that checks if TurboModules are enabled, don't expose them to JS via the old module system.
All TurboModules needs to implement TurboModule interface.

Reviewed By: mdvacca

Differential Revision: D13648332

fbshipit-source-id: f22506fe029ac82d56075f5b6962ff2df2e7eaa4

ReactAndroid/src/main/java/com/facebook/react/NativeModuleRegistryBuilder.java

@@ -8,6 +8,7 @@ package com.facebook.react;
 import com.facebook.react.bridge.ModuleHolder;
 import com.facebook.react.bridge.NativeModuleRegistry;
 import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.config.ReactFeatureFlags;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -55,6 +56,17 @@ public class NativeModuleRegistryBuilder {
         }
         mModules.remove(existingNativeModule);
       }
+      if (ReactFeatureFlags.useTurboModules && moduleHolder.isTurboModule()) {
+        // If this module is a TurboModule, and if TurboModules are enabled, don't add this module
+
+        // This condition is after checking for overrides, since if there is already a module,
+        // and we want to override it with a turbo module, we would need to remove the modules thats
+        // already in the list, and then NOT add the new module, since that will be directly exposed
+
+        // Note that is someone uses {@link NativeModuleRegistry#registerModules}, we will NOT check
+        // for TurboModules - assuming that people wanted to explicitly register native modules there
+        continue;
+      }
       mModules.put(name, moduleHolder);
     }
   }