Introduce a new field Severity to UnmarshalError. It helps users distinguish different UnmarshalError severity levels.
Introduce a new field Severity to UnmarshalError. It helps users distinguish different UnmarshalError severity levels.

PiperOrigin-RevId: 387473899

google/fhir,google/fhir,google/fhir,google/fhir,google/fhir,google/fhir