Fix incorrect override of equals in FlipperArray, FlipperObject

Summary:
mityal implemented a new check for nullsafe to warn about potentially
incorrect overrides of `equals` method (not yet released).

While testing some other things I stumbled upon incorrect `equal`
overrides in Flipper, particularly not properly handling `null` param.

Reviewed By: passy

Differential Revision: D19639882

fbshipit-source-id: 7f9aec7270e89a906810807f6849628967047b2a

android/src/main/java/com/facebook/flipper/core/FlipperArray.java

@@ -9,6 +9,7 @@ package com.facebook.flipper.core;
 
 import java.util.ArrayList;
 import java.util.List;
+import javax.annotation.Nullable;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -89,8 +90,12 @@ public class FlipperArray {
   }
 
   @Override
-  public boolean equals(Object o) {
-    return mJson.toString().equals(o.toString());
+  public boolean equals(@Nullable Object o) {
+    if (o == null) {
+      return false;
+    } else {
+      return mJson.toString().equals(o.toString());
+    }
   }
 
   @Override

android/src/main/java/com/facebook/flipper/core/FlipperObject.java

@@ -8,6 +8,7 @@
 package com.facebook.flipper.core;
 
 import java.util.Arrays;
+import javax.annotation.Nullable;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -82,8 +83,12 @@ public class FlipperObject {
   }
 
   @Override
-  public boolean equals(Object o) {
-    return mJson.toString().equals(o.toString());
+  public boolean equals(@Nullable Object o) {
+    if (o == null) {
+      return false;
+    } else {
+      return mJson.toString().equals(o.toString());
+    }
   }
 
   @Override