replace stream with iterator

Signed-off-by: Sebastian Schüpbach <sebastian.schuepbach@unibas.ch>
3 jobs for master in 5 minutes and 22 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed test-sbt #71023
mbr

00:02:44

 
  Build
passed assembly-sbt #71024
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00:02:10

 
  Publish
passed build-latest-image #71025
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00:00:27