[ResourceBundle] check also for empty "pimcore_class_name"

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Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Fixed tickets	#...

[github-actions[bot]]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

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I have read the CLA Document and I hereby sign the CLA