signedMetadata
Serve this result serialized at the path formed by inserting the string /.well-known/openid-credential-issuer (see OpenIdConstants.WellKnownPaths.CredentialIssuer) into the Credential Issuer Identifier between the host component and the path component, if any. Use this only when the client accepts (see Accept header io.ktor.http.HttpHeaders.Accept) the media type application/jwt (see at.asitplus.wallet.lib.data.MediaTypes.Application.JWT), otherwise serve metadata.
Implements OID4VCI 1.0, Section 12.2.3, i.e. sets typ to OpenIdConstants.ISSUER_METADATA_JWT_TYPE and adds the claims sub and iat to metadata.