docs: @Override
      public String getSignature(String baseString, String apiSecret, String tokenSecret) {
          try {
              final Signature signature = Signature.getInstance(RSA_SHA1);
              signature.initSign(privateKey);
              signature.update(baseString.getBytes(UTF8));
              return BASE_64_ENCODER.encodeToString(signature.sign());
          } catch (NoSuchAlgorithmException | InvalidKeyException | SignatureException | UnsupportedEncodingException |
                  RuntimeException e) {
              throw new OAuthSignatureException(baseString, e);
          }
      }