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Add DocuemntVersion schema plugin to define version key for optimistic locking
Add UpdatedOn schema plugin for createdOn auto generating and populating
Add CreatedBy schema plugin for createdBy auto populating
Add UpdatedBy schema plugin for updatedBy auto populating
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plug DocumentVersion, CreatedBy, UpdatedOn and UpdatedBy plugins
Add Thing model in replace of Deal in the future
Add mock and test for Thing model