title: EL expression: passing null as value of BigDecimal field
body: <p>I have class with <code>BigDecimal</code> property. When I bind to it EL expression and passing null - <code>valueExpression.set(context, null)</code>, new value of property becomes to be <code>BigDecimal.ZERO</code>.</p>
  
  <p>Is there any way to pass null to <code>BigDecimal</code> field without converting it to zero?</p>