*/
@Override
@SuppressWarnings("unchecked")
protected Object convert(AggregationExpressionTransformationContext<LiteralNode> context) {
LiteralNode node = context.getCurrentNode();
Object value = node.getValue();
if (context.hasPreviousOperation()) {
if (node.isUnaryMinus(context.getParentNode())) {
// unary minus operator
return NumberUtils.convertNumberToTargetClass(((Number) value).doubleValue() * -1,
(Class<Number>) value.getClass()); // retain type, e.g. int to -int
}