This must be 1:1 with members of our oneofs, it can be used for filtering Note and Occurrence on their kind.

PACKAGE_VULNERABILITY The note and occurrence represent a package vulnerability.
BUILD_DETAILS The note and occurrence assert build provenance.
IMAGE_BASIS This represents an image basis relationship.
PACKAGE_MANAGER This represents a package installed via a package manager.
DEPLOYABLE The note and occurrence track deployment events.
DISCOVERY The note and occurrence track the initial discovery status of a resource.
ATTESTATION_AUTHORITY This represents a logical "role" that can attest to artifacts.
UPGRADE This represents an available software upgrade.