How to extract email subjects using the Google mail audit API without using FULL_MESSAGE?

Question

When doing an email dump of a user's account using the Google Mail Audit API I have been able to extract the subject data only if I use FULL_MESSAGE when making the request. However, this does downloads much more than what I need (attachments, mail bodies etc..). All I want is the To, Cc, Bcc and From information and the subject line for each email.

Using the HEADERS_ONLY option in the request gives all this information except for the subject info. Is it possible for subject line data to be added to the HEADERS_ONLY extraction output?