Updated to avoid deprecation of encode and decode methods in multi_json gem.

lib/google/api_client/reference.rb

@@ -103,7 +103,7 @@ module Google
       
       def serialize_body(body)
         return body.to_json if body.respond_to?(:to_json)
-        return MultiJson.encode(options[:body_object].to_hash) if body.respond_to?(:to_hash)
+        return MultiJson.dump(options[:body_object].to_hash) if body.respond_to?(:to_hash)
         raise TypeError, 'Could not convert body object to JSON.' +
                          'Must respond to :to_json or :to_hash.'
       end