code: public ValueExpression getValueExpression(String name) {
  
          if (name == null) {
              throw new NullPointerException();
          }
  
          Map<String,ValueExpression> map = (Map<String,ValueExpression>)
                getStateHelper().get(UIComponentBase.PropertyKeys.bindings);
          return ((map != null) ? map.get(name) : null);
  
      }
docs: <p>Return the {@link ValueExpression} used to calculate the value for the
  specified attribute or property name, if any.</p>
  
  <p>This method must be overridden and implemented for components that
  comply with JSF 1.2 and later.</p>
  
  @since 1.2
  
  @param name Name of the attribute or property for which to retrieve a
  {@link ValueExpression}
  
  @throws NullPointerException if <code>name</code>
  is <code>null</code>