OptionaltrustNon-empty list of trusted trust anchor URLs. When provided, traversal
stops as soon as one of these URLs is reached and the resolved chain root
is verified against the list. When omitted, traversal follows
authority_hints until no further hints exist (or a cycle / depth limit
is hit), and any chain root is accepted — callers are responsible for
applying their own root-of-trust verification in that case.
Required for hashing operations, used to compute JWK thumbprints when comparing key material across subordinate statements and entity configurations.