public String getProperty(String key, boolean mandatory) throws DAOConfigurationException {
        String fullKey = specificKey + "." + key;
        String property = PROPERTIES.getProperty(fullKey).toString();

        if (property == null || property.trim().length() == 0) {
            if (mandatory) {
                throw new DAOConfigurationException("Required property '" + fullKey + "' is missing in properties file '" + PROPERTIES_FILE + "'.");
            } else {
                property = null;
            }
        }

        return property;
    }