Add tests #2
Description
Shamelessly plug test from https://github.com/swordapp/JavaServer2.0/pull/12/files#diff-2028ffc93ede71749545641d956f9eeacb1720c301b9a401debe2081b244cb3b
Do we want sth. like those from https://github.com/MyCoRe-Org/easy-sword2-lib/tree/master/src/test/java/org/swordapp/server ? (Either using Jetty or Undertow + JUnit 5 extension)
Maybe incorporate https://github.com/DANS-KNAW/easy-sword2-dans-examples for more tests.