includeProperties in Json struts2 plugin not working

Assuming the fields in your FilterType are named id and desc

Try

<param name="includeProperties">
filterList\[\d+\]\.id,
filterList\[\d+\]\.desc
</param>

Struts2-json plugin will seralize your all action attributes in the action class.

Its a problem that I had faced using struts2-json-plugin. Even though the plugin-doc show a working examples for includeProperties parameter, it never worked for me and never did after so many trials and googling. So i had to use excludeProperties to remove non-required contents from being serialized, instead of specifying what I want to serialize.