Improve saveObject Method: Remove Persistence File for Empty SharedObject Instances

[mercuryVM]

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Pull Request

This pull request improves the saveObject method in the FilePersistence.java file by adding a check for empty SharedObject instances. If a SharedObject is empty (i.e., it has no attributes), the corresponding persistence file is now deleted. This prevents the server from loading outdated or unnecessary data in the future.

[mercuryVM]

Currently, even when forcing a clear on the SharedObject, its persistent data remains. This has proven to be an issue in my application, and I'm not sure if this is the correct behavior.