The feature implemented in JENKINS-41497 uses a different default behavior for implicitly loaded libraries and the static import of a shared library
than for the dynamic import
I would expect that if the changelog parameter is not specified, the library step would also obtain the default value from the global library configuration.
The workaround to use the decorator syntax is impractical for me because it would require changes to a large number of Jenkinsfiles.
It seems like my expected behavior might have been intended originally. In the implementation in LibraryStep.java
a function is called that loads the global configuration value if the argument is null, but due to the default initialization, this statement only has effect if changelog = null is specified explicitly.