Ah yes, and (following [1]) I also changed the .pom file in
/usr/share/java/slf4j-simple.jar to remove the "test" scope:
--- pom.xml 2018-11-02 16:50:02.705092444 +0100
+++ pom.xml.orig 2018-11-02 16:50:17.793353153 +0100
@@ -30,9 +30,9 @@
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
- <!--<type>test-jar</type> -->
+ <type>test-jar</type>
<version>1.7.25</version>
- <!--<scope>test</scope> -->
+ <scope>test</scope>
</dependency>
</dependencies>
</project>
Perhaps that's needed as well, I didn't revert and re-test.
Ad 1:
https://stackoverflow.com/questions/12926899/java-lang-noclassdeffounderror-org-slf4j-loggerfactory/25621130
