Add API to retrieve Java Object from Flipper objects

Summary: There's no existing API on the Flipper objects to get an arbitrary Java object, which we need in an inspector plugin we're building (`getDynamic` requires you to know what you want in the end).

Reviewed By: jknoxville

Differential Revision: D21223329

fbshipit-source-id: 29e9f8788be404cec44c6ddeb6b56b939b97b766

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

@@ -67,6 +67,18 @@ public class FlipperArray {
     return new FlipperArray((JSONArray) o);
   }
 
+  public Object get(int index) {
+    final Object o = mJson.opt(index);
+
+    if (o instanceof JSONObject) {
+      return new FlipperObject((JSONObject) o);
+    } else if (o instanceof JSONArray) {
+      return new FlipperArray((JSONArray) o);
+    } else {
+      return o;
+    }
+  }
+
   public int length() {
     return mJson.length();
   }

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

@@ -69,6 +69,18 @@ public class FlipperObject {
     return new FlipperArray((JSONArray) o);
   }
 
+  public Object get(String name) {
+    final Object o = mJson.opt(name);
+
+    if (o instanceof JSONObject) {
+      return new FlipperObject((JSONObject) o);
+    } else if (o instanceof JSONArray) {
+      return new FlipperArray((JSONArray) o);
+    } else {
+      return o;
+    }
+  }
+
   public boolean contains(String name) {
     return mJson.has(name);
   }