docs: public String sign(RawTransaction rawTransaction) {
  
          byte[] signedMessage;
  
          if (chainId > ChainId.NONE) {
              signedMessage = TransactionEncoder.signMessage(rawTransaction, chainId, credentials);
          } else {
              signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials);
          }
  
          return Numeric.toHexString(signedMessage);
      }