Fix entry gets deleted after aux import

[Siedlerchr]

Set changed flag on clone also for Misc entry type, because otherwise it equals the default entry type and no change is triggered which results in the entry not beeing written to the database on save
Fixes #6405

Simplify gui code

• Change in CHANGELOG.md described (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked documentation: Is the information available and up to date? If not created an issue at https://github.com/JabRef/user-documentation/issues or, even better, submitted a pull request to the documentation repository.

[koppor]

I would doubt that this fixed the issue for the other types. -- When the entry type is Article, the clone is unchanged, too. Thus, no serialization written

[Siedlerchr]

New BibEntryType(entryType) always calls setType() and thus:
The default value for field.get is the default entry type misc.

jabref/src/main/java/org/jabref/model/entry/BibEntry.java

Lines 360 to 371 in 7cc5747

	public Optional<FieldChange> setType(EntryType newType, EntriesEventSource eventSource) {
	Objects.requireNonNull(newType);
	EntryType oldType = type.get();
	if (newType.equals(oldType)) {
	return Optional.empty();
	}
	changed = true;
	this.type.setValue(newType);
	FieldChange change = new FieldChange(this, InternalField.TYPE_HEADER, oldType.getName(), newType.getName());

[Siedlerchr]

For all other non default entry types the change flat is correclty set that was what this issue made so special.

[tobiasdiez]

I wouldn't update the changed flag. The clone method should really clone the original entry, without any modifications (otherwise its not a clone).

However, the aux importer should set the changed flag of all entries (regardless of type), so that they get properly reformatted when writing them to disc (i.e. not using the parsed serialization of the original bib file).

[Siedlerchr]

Well, the clone method implicitly sets the changed flags for all entry types except the default entry type.
The aux importer has nothing to do with this changed or serialization stuff. It's only relevant for saving the newly created library. I don't see any reason to add this logic to the AuxImporter
Only the BibTexParser does it.

[tobiasdiez]

I wouldn't update the changed flag. The clone method should really clone the original entry, without any modifications (otherwise its not a clone).

However, the aux importer should set the changed flag of all entries (regardless of type), so that they get properly reformatted when writing them to disc (i.e. not using the parsed serialization of the original bib file).

[koppor]

@calixtus and me implemented all required changes.

[Siedlerchr]

Manually tested the changes again, All good. Merge now