Feature request: check regular expressions

[networkinss]

It would be convenient if you could define fields with regular expressions.
Like it is with excludeProperties, just instead to ignore the fields it is tested againg a regular expression (mail format, timestamp etc).

[elans3]

Can you provide more details about this use case with appropriate examples

[networkinss]

Currently there is only string comparison (see #212).
If would be good if you could define a regular expression
to check if it has a mail format value or a URL format or UUID.
Things like that would make it much better to check for the contract.