docs: public String getPublicKey() {
          RSAPublicKey key = InstanceIdentityProvider.RSA.getPublicKey();
          if (key == null) {
              return null;
          }
          byte[] encoded = Base64.encodeBase64(key.getEncoded());
          int index = 0;
          StringBuilder buf = new StringBuilder(encoded.length + 20);
          while (index < encoded.length) {
              int len = Math.min(64, encoded.length - index);
              if (index > 0) {
                  buf.append("\n");
              }
              buf.append(new String(encoded, index, len, Charsets.UTF_8));
              index += len;
          }
          return String.format("-----BEGIN PUBLIC KEY-----%n%s%n-----END PUBLIC KEY-----%n", buf.toString());
      }