details.descriptor cannot be resolved or is not a field

Symptom:
Compilation error in generated code: details.descriptor cannot be resolved or is not a field
Cause:
The "descriptor" association between the <EvidenceEntity>Details struct and the EvidenceDescriptorDetails struct 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.