code: private TransactionReceipt send(String toAddress, BigDecimal value, Convert.Unit unit)
              throws IOException, InterruptedException,
              TransactionException {
  
          BigInteger gasPrice = requestCurrentGasPrice();
          return send(toAddress, value, unit, gasPrice, GAS_LIMIT);
      }
docs: Given the duration required to execute a transaction, asyncronous execution is strongly
  recommended via {@link Transfer#sendFunds(String, BigDecimal, Convert.Unit)}.
  
  @param toAddress destination address
  @param value amount to send
  @param unit of specified send
  
  @return {@link Optional} containing our transaction receipt
  @throws ExecutionException if the computation threw an
  exception
  @throws InterruptedException if the current thread was interrupted
  while waiting
  @throws TransactionException if the transaction was not mined while waiting