Implement negation of query filter closer to underlying API. Previously andNot() negated the whole filter and it's usage in IsUnique was actually a misunderstanding. Having not() as in javax.persistence.criteria.Predicate seems to be more intuitive for negating the whole filter and more flexible.

insert into stammdaten.verwaltungsgrenze(gem_id, shape)
SELECT 
  verwaltungseinheit.id,
  gem_utm.geom
FROM 
  stammdaten.verwaltungseinheit
left join geo.gem_utm on verwaltungseinheit.id = gem_utm.ags;