OJS XML import error foreign key constraint fails

Hi. This problem is related to:

Problem description:
I took the pkp OJS test import file here:

which works just fine on the import.

I replaced the submission_file/file/embed tag with href tag
(example: <href src="https://hcmc.uvic.ca/~mholmes/ojs/christensen_1_15.pdf" mime_type="application/pdf"/>).

In the file tag I removed the filesize attribute and changed the @extension to .pdf

When running an import I get the error below. It seems href file imports do not work.

[19-Nov-2021 15:24:53 America/Edmonton] PHP Notice: Undefined variable: newFileId in /var/www/sites/scancan/lib/pkp/plugins/importexport/native/filter/NativeXmlSubmissionFileFilter.inc.php on line 338
[19-Nov-2021 15:24:53 America/Edmonton] PHP Fatal error: Uncaught PDOException: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (jrnl_scancan.submission_files, CONSTRAINT submission_files_file_id_foreign FOREIGN KEY (file_id) REFERENCES files (file_id)) in /var/www/sites/scancan/lib/pkp/lib/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php:115
Stack trace:
#0 /var/www/sites/scancan/lib/pkp/lib/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php(115): PDOStatement->execute(NULL)
#1 /var/www/sites/scancan/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(464): Doctrine\DBAL\Driver\PDOStatement->execute()
#2 /var/www/sites/scancan/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(664): Illuminate\Database\Connection->Illuminate\Database{closure}(‘insert into `su…’, Array)
#3 /var/www/sites/scancan/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(631): Illuminate\Database\Connection- in /var/www/sites/scancan/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php on line 671

I believe filesize is the culprit. Is this attribute mandatory?

The filesize attribute does look mandatory as the import now seems to work properly although we are running into another problem where pdf’s are not showing up which I am not sure yet if it’s related. One thing I noticed is the physical file names are random alphanumeric names like:

and not the typical structure of various ID’s from the database. Is this supposed to happen?