'@ObjectModel.semanticKey' must be annotated at view

What causes this issue?

The usually highly denormalized search-views need a key definition that
reduces the cartesian product defined by the view as such to the entity
that is actually to be found. For this purpose, annotation
@ObjectModel.semanticKey (to be annotated at the view-level) is used.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Define the actual entity key by annotation @ObjectModel.semanticKey.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.