A NPE in AttatchmentDataSource could be guarded.

If I do a release a hold on a DataSource like this:

void release(DataSource ds) throws IOException {
AttachmentDataSource ads = getAttachmentDataSource(ds);
if (ads != null)

{ // tell attachment to hold the temporary file; ads.release(); }

}

and the ads.isCached() is false, I get a NPE. I know that without a hold() there should be no release(), but sometimes it may happen anyway (e.g. in finally blocks), and then it would not be necesarry to check isCahced() before.