in server/src/jetbrains/buildServer/vsoRooms/notificator/VSONotificator.java [166:171]
public void notifyBuildProblemResponsibleAssigned(@NotNull Collection<BuildProblemInfo> buildProblems, @NotNull ResponsibilityEntry entry, @NotNull SProject project, @NotNull Set<SUser> users) {
final Map<String, Object> root = myMessageBuilder.getBuildProblemsResponsibilityAssignedMap(buildProblems, entry, project, users);
root.put("responsibleUser", getUserDisplayName(entry.getResponsibleUser()));
root.put("reporterUser", getUserDisplayName(entry.getReporterUser()));
sendNotification(users, root, BUILD_PROBLEM_RESPONSIBILITY_ASSIGNED);
}