How to read content in a batch request

Hello,

We are doing a batch request with below payload.

PUT SubstitutionPeriodSet(SubstitutedPerNr='12345678',Begda=datetime'2015-07-14T00%3A00%3A00',Endda=datetime'2015-07-30T00%3A00%3A00') HTTP/1.1
Accept-Language: de
Accept: application/json
MaxDataServiceVersion: 2.0
DataServiceVersion: 2.0
Content-Type: application/json
Content-Length: 114
{"SubstitutedPerNr":"12345678","Begda":"\/Date(1436832000000)\/","Endda":"\/Date(1438300800000)\/","Leaveflag":""}

The method /IWBEP/IF_MGW_APPL_SRV_RUNTIME~CHANGESET_PROCESS is implemented for processing. We are able to get the entry key with below code.

ls_changeset_request-entry_provider->read_entry_data( IMPORTING es_data = ls_subst ).

My question: How can i get the body of the request. In this case content of below line.

{"SubstitutedPerNr":"10096395","Begda":"\/Date(1436832000000)\/","Endda":"\/Date(1438300800000)\/","Leaveflag":""}

Thanks

Pradeep