protected void insert(final String entryDN, final Attributes entry, final Supplier<Hashtable<String, String>> envSupplier) {
        try (DirContextHolder holder = getDirContext(envSupplier)) {
            logger.debug("Inserting LDAP entry: dn={}", entryDN);
            holder.get().createSubcontext(entryDN, entry);
        } catch (final NamingException e) {
            throw new LdapOperationException("Failed to add " + entryDN, e);
        }