Permissions of composer entry under external link

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For a project we have some external links, under which some composer entries will be published.

When I publish a composer entry under an external link, the permissions for this composer entry are "empty" (no permissions are assigned). Is there any way to fix this? I thought of firing some code on the on_composer_publish event, but I can not find some decent documentation regarding collection permissions.

Any help is welcome :-) !

emielmolenaar