fix ReadableNativeMap.toHashMap() for nested maps and arrays

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Commit 7891805d22 broke the previous behavior of `ReadableNativeMap.toHashMap()` for nested maps and arrays. Previously, all nested `ReadableNativeMap`s and `ReadableNativeArray`s were recursively converted to `HashMap`s and `ArrayList`s, but this is lost when only `getLocalMap()` is returned.

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Call `ReadableNativeMap.toHashMap()` on a map with values of type `ReadableNativeMap` and `ReadableNativeArray`. Verify the returned hash map has these converted to `HashMap` and `ArrayList`, respectively.

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[ANDROID] [BUGFIX] [ReadableNativeMap] - Fix toHashMap() for nested maps and arrays

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Closes https://github.com/facebook/react-native/pull/18455

Reviewed By: kathryngray

Differential Revision: D7347344

Pulled By: mdvacca

fbshipit-source-id: af2bca9dec6c0cb8a7da099b6757434fcc3ac785

ReactAndroid/src/main/java/com/facebook/react/bridge/ReadableNativeMap.java

@@ -11,6 +11,7 @@ import com.facebook.jni.HybridData;
 import com.facebook.proguard.annotations.DoNotStrip;
 
 import java.util.HashMap;
+import java.util.Iterator;
 
 import com.facebook.infer.annotation.Assertions;
 import javax.annotation.Nullable;
@@ -248,7 +249,31 @@ public class ReadableNativeMap extends NativeMap implements ReadableMap {
         }
       return hashMap;
     }
-    return getLocalMap();
+
+    // we can almost just return getLocalMap(), but we need to convert nested arrays and maps to the
+    // correct types first
+    HashMap<String, Object> hashMap = new HashMap<>(getLocalMap());
+    Iterator iterator = hashMap.keySet().iterator();
+
+    while (iterator.hasNext()) {
+      String key = (String) iterator.next();
+      switch (getType(key)) {
+        case Null:
+        case Boolean:
+        case Number:
+        case String:
+          break;
+        case Map:
+          hashMap.put(key, Assertions.assertNotNull(getMap(key)).toHashMap());
+          break;
+        case Array:
+          hashMap.put(key, Assertions.assertNotNull(getArray(key)).toArrayList());
+          break;
+        default:
+          throw new IllegalArgumentException("Could not convert object with key: " + key + ".");
+      }
+    }
+    return hashMap;
   }
 
   /**