Fix loading of long properties

[kirmerzlikin]

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https://github.com/quartz-scheduler/contributing/blob/main/CONTRIBUTING.md

Changes

• loading longs as longs instead of ints

Checklist

• tested locally
• updated the docs
• added appropriate test
• signed-off on the above mentioned SoftwareAG contributor agreement via git commit -s on my commits.
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Fixes #1140

PS: Yes, I know that this project seems to be abandoned (#1134)