Is there any function returns the value in thumbnails field in CFeedbackClient ?

Dear all,

I have a specific question concerning using GIFT client.

In my project, not only the url of the image is important, but also a 
value called "record ID" is important.
Record ID is the identifier of a record, which might contain one or more 
images.

As record id is not deductible from the image url, a hashmap must be 
built to bridge "url->recordID"

I have two choices, either stock this information in a separate file, or 
put it in url2fts.xml.

To stock it in a separate file is not a good idea, as my client will be 
only run via a web-service call,
which means every time when I need to perform a query, I need to reload 
the separate file to build the hashmap.....
which is not optimal if there are many image urls, or there are many 
queries at the same time.

Now if I choose the second solution, I put the record ID in the 
thumbnail field, as I do not really need the thumbnail.
The question is, with CFeedbackClient->getResultList() only "image url 
<-> relevance" pairs are obtained.

How can I get the value in thumbnails field ?? I looked into 
CFeedbackClient.pm but have not found suitable functions.

Cheers, Xin