public SecurityValidationContext initializeContext() {
SecurityValidationContext context = new SecurityValidationContext();
context.addExistingUserIds();
context.addExistingRoleIds();
context.addExistingPrivilegeIds();
for (CUser user : listUsers()) {
context.getExistingUserIds().add(user.getId());
context.getExistingEmailMap().put(user.getId(), user.getEmail());