Before this commit
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When we post a Customer Invoice by adding 2 products first one has a positive
unit value and the second one has a negative unit value than the wrong JSON
is generated.
The issue happens because of abs method converts the negative value into a positive.
After this commit
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In this commit, we are using the sign amount instead of the abs method.
Effected from this PR https://github.com/odoo/odoo/pull/99401closesodoo/odoo#104876
X-original-commit: 99b99bc672a54665b59efaa3a4e696f6250065c3
Signed-off-by: Josse Colpaert <jco@odoo.com>