in teamcity-invitations-plugin-server/src/main/java/org/jetbrains/teamcity/invitations/JoinProjectInvitationType.java [123:130]
public InvitationImpl createNewInvitation(@NotNull HttpServletRequest request, @NotNull SProject project, @NotNull String token) {
String name = request.getParameter("name");
String roleId = !StringUtil.isEmptyOrSpaces(request.getParameter("role")) ? request.getParameter("role") : null;
String groupKey = !StringUtil.isEmptyOrSpaces(request.getParameter("group")) ? request.getParameter("group") : null;
String welcomeText = StringUtil.emptyIfNull(request.getParameter("welcomeText"));
boolean multiuser = Boolean.parseBoolean(request.getParameter("multiuser"));
return createNewInvitation(SessionUser.getUser(request), name, token, project, roleId, groupKey, multiuser, welcomeText);
}