Message type: E = Error
Message class:  SADL_GW_DT_CDS - Messages CDS Checks 
Message number: 087
Message text: &1: Element &2 must be annotated with &3
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The SAP error message SADL_GW_DT_CDS087 typically occurs in the context of Core Data Services (CDS) views and the SAP Gateway. This error indicates that a specific element in your CDS view is missing an annotation that is required for the proper functioning of the service.
Cause: The error message SADL_GW_DT_CDS087 &1: Element &2 must be annotated with &3 can be broken down as follows: &1: This is the name of the CDS view or entity. &2: This is the name of the element (field) that is causing the issue. &3: This is the required annotation that is missing. The cause of this error is typically due to: Missing Annotations: The element in the CDS view does not have the necessary annotations that are required for the SAP Gateway to expose the data correctly. Incorrect Configuration: The CDS view may not be configured properly to meet the requirements of the OData service.
Solution: To resolve this error, you need to ensure
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