uom in customer return lines

[metas-lc]

Is this a bug or feature request?

bug

What is the current behavior?

uom piece is set by default when you want to create a new line, even if the product is on kg

Which are the steps to reproduce?

1. go to customer return window and create a new one
   https://w101.metasfresh.com:8443/window/53097
2. add all mandatory fields, doctype Kundenwarenrückgabe
3. add a line with a kg product (topinambour), add HUs
   =>
   Error: Ihr Test hat einen...
   Server error
   Ihr Test hat einen bisher unentdeckten Fehler offengelegt.
   Bitte leiten Sie diese Meldung an metas weiter: Error: Failed to convert Qty=10.000000000000 of product=P002748 from UOM=Kilogramm to UOM=Stück

What is the expected or desired behavior?

we need a callout that when you add a product, the uom to be set directly, accordingly

[metas-ts]

cherry-picked to branch 2019-01-12

[metas-lc]

IT
tested the testcase above in both swing and webui => works fine, the uom is set accordingly to product's uom OK