How to: Unzip a ZIP file within a ZIP file, with incremental build functionality maintained

I have a (main) ZIP archive on a Nexus server with several other ZIP archives inside, and I need to
a) extract all **/.hpp from a certain ZIP archive
b) extract all **/
.hpp from all ZIP archives in the main archive

The only solution I found is to have one Copy task to unpack the main archive in some temp directory and have a second Copy task to look into the temp directory.

What bothers me is that I cannot delete the temp directory, or, if I do this, the first Copy task always downloads and creates the temp directory again - although the second Copy task has nothing to do.

What would be a recommended code pattern to unpack a zip in a zip, without having to maintain some intermediate directory or losing the incremental build functionality?
Thanks, Klaus