Sometimes entities have a natural key property that is not necessarily the entity (database) key. E.g. a vehicle is a BaseIdentityIdEntity but has a natural key “VIN” (Vehicle Identification Number).
The idea is that the (optional) natural key property of an entity could be specified in the CUBA meta model (within CUBA studio). Benefits are for example:
Mostly the user “knows” the natural key of an entity. In a foreign key relationship to an entity it would be faster for him to enter the natural key instead of opening the select screen. The fieldgroups could use “smart” SearchPickerFields that allow to search by the natural key by default (without any further custom implementation).
In distributed environment (where data are imported from other sources) it would be easy to implement a custom UUID creator (see https://www.cuba-platform.com/discuss/t/create-uuid-based-in-composite-key) that generates the UUID based on the specified natural key.