The return structure of BulkAssociatedIdEnumerator with Name '{0}' on Entity (External Content Type) with Name '{1}' and ...

The return structure of BulkAssociatedIdEnumerator with Name '{0}' on Entity (External Content Type) with Name '{1}' and Namespace '{2}' cannot store multiple identifier values. A collection is necessary between the root of the return structure and TypeDescriptors which define Identifiers.