code: @Override
      public SignatureVerifier getSignatureVerifier() throws Exception {
          try {
              HttpEntity<Void> request = new HttpEntity<>(new HttpHeaders());
  
              String content = restTemplate.exchange(getPublicKeyEndpoint(),
                  HttpMethod.GET, request, String.class).getBody();
  
              if (StringUtils.isEmpty(content)) {
                  log.info("Public key not fetched");
                  return null;
              }
  
              InputStream fin = new ByteArrayInputStream(content.getBytes());
              CertificateFactory f = CertificateFactory.getInstance("X.509");
              X509Certificate certificate = (X509Certificate) f.generateCertificate(fin);
              PublicKey pk = certificate.getPublicKey();
  
              return new RsaVerifier(String.format(PUBLIC_KEY, new String(Base64.getEncoder().encode(pk.getEncoded()))));
          } catch (IllegalStateException ex) {
              log.warn("could not contact Config to get public key");
              return null;
          }
      }
docs: Fetches the public key from the MS Config.
  
  @return the public key used to verify JWT tokens; or null.