add pdf to bib

[leaf-soba]

• follow up:Fix get title logic to ignore the first extra large character in the abstract #12137

1. remove double space in unit test
2. fix a logic bug about space.
3. skip the normal space in the title character
4. rename pdf use last name not first name

Mandatory checks

• I own the copyright of the code submitted and I licence it under the MIT license
• Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[github-actions]

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[github-actions]

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[koppor]

Small comment

[koppor]

Remove this line. - We do not distinguish between "unknown DOI" and no DOI available.

[koppor]

I think, there could be multiple spaces etc.

Suggested change

	if (" ".equals(textPosition.getUnicode())) {
	if (StringUtil.isBlank(textPosition.getUnicode())) {