Promote Close() to the interface level

Author: erm-g

security/advancedtls/crl_provider.go

@@ -52,6 +52,9 @@ type CRLProvider interface {
 	//
 	// [RFC5280 - Undetermined]: https://datatracker.ietf.org/doc/html/rfc5280#section-6.3.3
 	CRL(cert *x509.Certificate) (*CRL, error)
+
+	// Close cleans up resources allocated by the provider.
+	Close()
 }
 
 // StaticCRLProvider implements CRLProvider interface by accepting raw content
@@ -87,6 +90,9 @@ func (p *StaticCRLProvider) CRL(cert *x509.Certificate) (*CRL, error) {
 	return p.crls[cert.Issuer.ToRDNSequence().String()], nil
 }
 
+// Close is a no-op.
+func (p *StaticCRLProvider) Close() {}
+
 // FileWatcherOptions represents a data structure holding a configuration for
 // FileWatcherCRLProvider.
 type FileWatcherOptions struct {