Fixed issue with header/options ambiguity.

spec/google/api_client/discovery_spec.rb

@@ -14,6 +14,7 @@
 
 require 'spec_helper'
 
+require 'json'
 require 'signet/oauth_1/client'
 require 'httpadapter/adapters/net_http'
 
@@ -238,6 +239,19 @@ describe Google::APIClient do
         )
       end).should raise_error(Google::APIClient::ClientError)
     end
+
+    it 'should correctly handle unnamed parameters' do
+      @client.authorization = :oauth_2
+      @client.authorization.access_token = '12345'
+      result = @client.execute(
+        @prediction.training.insert,
+        {},
+        JSON.generate({"id" => "bucket/object"}),
+        {'Content-Type' => 'application/json'}
+      )
+      method, uri, headers, body = result.request
+      Hash[headers]['Content-Type'].should == 'application/json'
+    end
   end
 
   describe 'with the buzz API' do