Best practice to compare if extended object contains values of old object

Lest pretend I have object like:

FirstName = "A"
LastName = "B"
DateOfBirth = "17"
Age = "1999-06-17"

From now after I add some additional fields and now my object is

FirstName = "A"
LastName = "B"
DateOfBirth = "17"
Age = "1999-06-17"
AddressObject
         {
          AddressType = primary
          Street = "My street"
          Building = 11
         }

Qhat is the best solution to compare objects and see that old fields are same and added new referance object Address is not empty in JAVA.