Returns the list of field keys associated with a given coverage type.
Fields are sourced from both the database (entity_type_fields table)
and static configuration, then merged and deduplicated. The returned
field keys are human-readable strings (e.g., “reportDate”) that match
the keys used in event data objects.
Required permission: company.event:export
API key authentication. Include your API key in the Authorization header.
Company identifier
Coverage type identifier (e.g., "general_liability")