docs: @ReadOperation(produces = MediaType.TEXT_PLAIN_VALUE)
      public String fetchPublicKey(@Nullable final String service) throws Exception {
          val factory = KeyFactory.getInstance("RSA");
          var signingKey = tokenCipherExecutor.getSigningKey();
  
          if (StringUtils.isNotBlank(service)) {
              val registeredService = this.servicesManager.findServiceBy(service);
              RegisteredServiceAccessStrategyUtils.ensureServiceAccessIsAllowed(registeredService);
              val serviceCipher = new RegisteredServiceJwtTicketCipherExecutor();
              if (serviceCipher.supports(registeredService)) {
                  val cipher = serviceCipher.getTokenTicketCipherExecutorForService(registeredService);
                  if (cipher.isEnabled()) {
                      signingKey = cipher.getSigningKey();
                  }
              }
          }
  
          if (signingKey instanceof RSAPrivateCrtKey) {
              val rsaSigningKey = (RSAPrivateCrtKey) signingKey;
              val publicKey = factory.generatePublic(new RSAPublicKeySpec(rsaSigningKey.getModulus(), rsaSigningKey.getPublicExponent()));
              return EncodingUtils.encodeBase64(publicKey.getEncoded());
          }
          return null;
      }