while removing flow from dataStore md-sal is not filling flags (of type bits)

flow is defined as follows:
model-flow-base:opendaylight-flow-types.yang
...
typedef flow-mod-flags {
type bits

{ bit CHECK_OVERLAP; bit RESET_COUNTS; bit NO_PKT_COUNTS; bit NO_BYT_COUNTS; bit SEND_FLOW_REM; }

}
after creating flow, rest exposes correct content of field 'flags':
<flags>FlowModFlags [_cHECKOVERLAP=false, _rESETCOUNTS=false, _nOPKTCOUNTS=false, _nOBYTCOUNTS=false, _sENDFLOWREM=false]</flags>

While removing this flow, md-sal looks up flow by path and found flow has field 'flags' set to null.