Accessing Role Assignments of a specific team area,RTC version 6.0.1

i want to obtain Role Assignments of a specific team area, i found there is a answer: https://jazz.net/forum/questions/244677/accessing-role-assignments-of-a-specific-team-area-via-rest-api

But when i call https://url.of.server:port/appContextRoot/service/com.ibm.team.process.internal.service.web.IProcessWebUIService/teamAreaByUUIDWithLimitedMembers?processAreaItemId=<teamAreaUUID>

i got soap response, but result is below, not the same format with which in up page :

<memberIds>_d6jq8HbnEeWNLZ46zq9y-w</memberIds>
<memberIds>_O6pSoDN_Eea5SZheswfS2Q</memberIds>
<memberIds>_oAV10HewEeWNLZ46zq9y-w</memberIds>
<memberIds>_xwyC0Hh5EeWNLZ46zq9y-w</memberIds>
<memberIds>_ixSpUHf4EeWR35sdp0prNw</memberIds>
i want to know the reason or another way to extract them.