RestDataSource and 'oldValues'

I'm using RestDataSource. I see 'oldValues' is not automatically added to DSRequest for update or remove operation. What is the problem? Thanks!

Here is what javadoc says:
“For an update or remove operation, the original values from the record that is being updated or removed. oldValues is automatically added to DSRequests submitted by DataBound Components. Available on the server via DSRequest.getOldValues()."

1. the *complete* SmartGWT or SmartClient version from the lower left-hand corner of the Developer Console (see FAQ for how to open Developer Console),

SmartClient Version: v9.0p_2014-01-09/EVAL Deployment (expires 2014.03.10_09.41.58) Licensed to: Isomorphic Software (#ISC_EVAL_NIGHTLY)

2. browser(s) and version(s) involved

Firefox 17

3. for a server-side problem, the *complete* logs generated during processing of the failing request (do *not* trim to just the error message)


=== 2014-03-01 01:15:27,925 [l0-7] DEBUG HttpProxyServlet - HttpProxy - ProxyData is: {
xsi:"http://www.w3.org/2000/10/XMLSchema-instance",
url:"http://localhost:8888/data/sampleRemoveData.js",
httpMethod:"POST",
params:{
isc_dataFormat:"json"
},
contentType:"application/json",
requestBody:"{\r \"dataSource\":\"isc_MyRestSample_3_0\", \r \"operationType\":\"remove\", \r \"componentId\":\"isc_ListGrid_1\", \r \"data\":{\r \"col1\":\"row2\", \r \"col2\":\"value2\", \r \"_selection_7\":true\r }, \r \"oldValues\":null\r}",
}
=== 2014-03-01 01:15:27,925 [l0-7] INFO HttpProxyServlet - HttpProxy - writing body: {
"dataSource":"isc_MyRestSample_3_0",
"operationType":"remove",
"componentId":"isc_ListGrid_1",
"data":{
"col1":"row2",
"col2":"value2",
"_selection_7":true
},
"oldValues":null
}

4. for any problem processing a server response, the actual response as shown in the RPC tab in the Developer Console

{"response":{"status":0,"data":[{"col1":"row1"}]}}