The business object is a Contract containing several attributes.
The ContractService is currently fetching the data from a simulated database, which takes some time to get the data.
Implements the pattern Proxy to cache.
In a second time, we want to restrict the access of a Contract only if the Contract has not expired, that is to say
the end date is before today.
Implements the pattern Proxy to restrict the access of the resource according to this rule.
Solution is under the package solution. Classes under this package are prefixed with the symbol ɵ to disable IDE autocompletion.