code: public TLSConfigurer trustedKeys(String... trustedKeys) {
          this.trustedKeys = Arrays.stream(trustedKeys).collect(toSet());
          return this;
      }
docs: When not set all certificates included in the keystore will be used as trusted certificate authorities. When
  specified,
  only keys with the defined aliases will be used for trust evaluation.
  <p>
  Alternatively use property:
  <pre>
  saml.sso.tls.trusted-keys
  </pre>
  </p>
  
  @param trustedKeys trusted keys.
  @return this configurer for further customization