docs: private RSAPrivateKey loadPrivateKeyFromPEMFile(String filename) {
          try {
              String publicKeyFile = FileReader.readFileFromClassPathOrPath(filename);
              byte[] publicKeyBytes = DatatypeConverter.parseBase64Binary(publicKeyFile.replace("-----BEGIN RSA PRIVATE KEY-----", "").replace("-----END RSA PRIVATE KEY-----", ""));
              return (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(publicKeyBytes));
          } catch (Exception e) {
              throw new RuntimeException("Exception reading private key from PEM file", e);
          }
      }