title: How to sum BigDecimal properties of objects in Java8 lambda expression?
body: <p>Let's get a simple real life example:</p>
  
  <pre><code>BigDecimal invoiceValue = BigDecimal.ZERO;
  for (InvoiceItem i : invoiceItems) {
      invoiceValue = invoiceValue.add(i.getItemValue());
  }
  </code></pre>
  
  <p>How to get this in one statement with Java8 lambda expression?</p>