return fessConfig.getRoleSearchGroupPrefix();
            }
        }
        return null;
    }

    /**
     * Escapes special characters in an LDAP search filter to prevent LDAP injection attacks.
     *
     * @param filter the LDAP search filter to escape (null is treated as empty string)
     * @return the escaped filter string safe for use in LDAP queries (empty string if filter is null)

        } catch (final Exception e) {
            logger.debug("Failed to get document count: indexName={}", indexName, e);
        }
        return -1;
    }

    /**
     * Gets the number of aliases attached to the specified index.
     *
     * @param indexName the name of the index
     * @return the number of aliases, or 0 if none found or an error occurred
     */
    public int getAliasCount(final String indexName) {