code: public ExtendedMetadataConfigurer trustedKeys(String... trustedKeys) {
          this.trustedKeys = Arrays.stream(trustedKeys).collect(toSet());
          return this;
      }
docs: Keys used as anchors for trust verification when PKIX mode is enabled for the local entity. In case value is
  null all keys in the keyStore will be treated as trusted.
  <p>
  Alternatively use property:
  <pre>
  saml.sso.extended-metadata.trusted-keys
  </pre>
  </p>
  
  @param trustedKeys the trusted key names
  @return this configurer for further customization