Fixed: Avoid displaying quantities equal to zero as 1 in the invoice items grid of the View Invoice screen (OFBIZ-13362)

Even when the invoice item quantity is correctly set to zero in the
database, the screen viewInvoice erroneously ‘visualize’ an invoice item
reporting one unit of the product.

The problem is due to the fact that the grid 'ListInvoiceItems' used in
the viewInvoice screen set the invoice item quantity to one when it is
zero. The change in the commit makes sure that the quantity visualized is
set to 1 only when the quantity is null.

(cherry picked from commit aef5f8e)

Author: golja

applications/accounting/widget/accounting/AccountingInvoiceItemCpd.xml

@@ -390,7 +390,7 @@ under the License.
             paginate-target="Accounting/Invoice/Items/List" odd-row-style="alternate-row" default-table-style="basic-table hover-bar"
             extends="CommonDynamicGrid" extends-resource="component://common/widget/CommonForms.xml">
             <wf:row-actions>
-                <wf:set field="quantity" value="${groovy: quantity ?: 1}" type="BigDecimal"/>
+                <wf:set field="quantity" value="${groovy: (quantity != null) ? quantity : 1}" type="BigDecimal"/>
                 <wf:set field="total" value="${groovy: quantity * amount ?: 0}" type="BigDecimal"/>
             </wf:row-actions>
             <wf:auto-fields-entity entity-name="InvoiceItem" default-field-type="display"/>