@SuppressWarnings("unchecked")
    private Function<?, String> newStringifier(String keyPattern, String className) {
        final Function<?, String> stringifier;
        try {
            stringifier = (Function<?, String>)
                    Class.forName(className, true, getClass().getClassLoader())
                         .getDeclaredConstructor()
                         .newInstance();
        } catch (Exception e) {
            throw new IllegalArgumentException("failed to instantiate a stringifier function: " +
                                               keyPattern, e);
        }
        return stringifier;
    }
Adds the property represented by the specified key pattern to the export list. Please refer to the
<a href="https://armeria.dev/docs/advanced-logging">Logging contextual information</a>
in order to learn how to specify a key pattern.
core/src/main/java/com/linecorp/armeria/common/logging/ExportGroupBuilder.java