Add equals and hashCode to MongoProperties

Because in my company we want to use them as key in HashMap, thus build a map from properties to MongoClient, and make it a cache pool.

Yes we have a mechanism to config multiple MongoProperties, and some of them are same, others not.

Comment From: snicoll

Thanks for the suggestion but we don't want to do this ad-hoc and adding equals/hashCode on all @ConfigurationProperties type can be tricky.