When using the command
"try to control ... with pi service ..."
I have to know which objects are currently not under PI control.
Otherwise I get the exception
Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "ukjevjp7l6m7banvyg5rw7ms3y4"
Detail: Key (identifier, type)=(urn:nbn:de:hbz:464-20190219-145710-2, dnbUrn) already exists.
PI service should tolerate objects that are already under its control and just skip