As suggested in https://discuss.elastic.co/t/logstash-jdbc-class-cannot-found/209807 I changed the driver library to
jdbc_driver_library => "c:/logstash/logstash-7.5.0/lib/jars/mariadb-java-client-2.4.2.jar"
but my jdbc connection via logstash 7.5 still don't work. Are we looking at a undokumented breaking feature?