Remove empty entries automatically

[koppor]

Fixes #8645.

Empty entries IMHO do not contain any information.

Exmaple for empty entries:

@misc{}

@article{}

With a citation key or any other field, they are not empty:

@misc{test}

@article{test2}

This PR adds a functionality so that these entries are automatically removed while writing.

Outdated

In case they are removed, JabRef will (udate NOT) issue a warning "changed on disk". I think, this warning is OK, isn't it?

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5. Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
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[Siedlerchr]

This defeats the purpose of the dialog. I would rather have an option to automatically always delete them

[koppor]

The dialog was there to warn about null information being in the library.

Is there anyone wanting to keep information that an entry with @article is in the database?

Back in #8096 (comment), we agreed that deleting the entries is a solution.

I updated the PR link to link the issue which explains why empty entries cause a headache: #8645

[Siedlerchr]

Not happy about this leading to a changed on disk

[koppor]

Not happy about this leading to a changed on disk

Fixed.

[koppor]

This (now) also fixes #8645, because isEmpty currently includes a check for auto generated fields:

@Article{,
  creationdate = {2022-04-05T10:41:54},
  owner        = {mlep},
}