in server/src/jetbrains/buildServer/vsoRooms/rest/impl/VSOTeamRoomsAPIConnectionImpl.java [39:45]
public TeamRoomMessage sendMessageToRoom(@NotNull String account, @NotNull Long roomId, @NotNull String messageContent){
final HttpHeaders requestHeaders = getRequestHeaders();
requestHeaders.setContentType(MediaType.APPLICATION_JSON);
final HttpEntity<String> request = new HttpEntity<String>(getMessageBody(messageContent), requestHeaders);
final ResponseEntity<TeamRoomMessage> responseEntity = myRestTemplate.postForEntity(getRoomMessagesUrl(account, roomId), request, TeamRoomMessage.class);
return responseEntity.getBody();
}