Invalid Mandatory Field

Symptom:
Error when build generated is called from EJBServer: The mandatory field 'dtls.<fieldName> specified for parameter 'dtls' of operation '<EntityName>.create<EntityName>Evidence' is invalid.
Cause:
The "dtls" association between the <EvidenceEntity>Details struct and the EvidenceEntity entity is missing. This association is mandatory for all evidence entities.
Solution:
Create an association as described between the two structs. See Asset Entity and Aggregations for more details.