Method Tax.get should be public
I need to use directly the Tax.get method.
(my use case is : I have to add c_tax_id, taxamt on the expense line table and i don't have any bpartner location (only org location). So i can't use getCharge or getProduct).
This patch contains the first and
set the getExemptTaxmethod as public
getExemptTaxreturn active tax records only