EnsureCreatedare used to create the database. On SQL Server, it will translate to the following SQL.
BillingAddressproperties have been configured as required.
Customer, and all the columns for any of the addresses are
null, instead of setting an empty instance of address.
BillingAddressnavigation can now be configured as a required dependent.
EnsureCreatedmethod, you will see that it will now include non-nullable columns for the required properties of the required dependent.