I have read the official MicroFocus article "How can I run a Silk4J test from the command line?" but doing as described results in the message
Exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/Logger
at org.apache.logging.slf4j.SLF4JLoggerContext.getLogger(SLF4JLoggerContext.java:41)
So it seems there are more JARs to be added to the class path than described in the article, which is from 2013.
It turns out I had too many JAR files in my classpath.
Removing the following JARs enhanced the situation:
log4j-to-slf4j-2.0.2.jarlog4j-to-slf4j-2.0.2-javadoc.jarlog4j-to-slf4j-2.0.2-sources.jarlog4j-slf4j-impl-2.0.2.jarlog4j-slf4j-impl-2.0.2-javadoc.jarlog4j-slf4j-impl-2.0.2-sources.jar(where the JavaDoc and Sources were probably not an issue).