The Hadoop token service loading (identifiers, renewers...) works provided there's no problems loading any registered implementation. If there's a classloading or classcasting problem, the exception raised will stop all token support working; possibly the application not starting.
This matters for S3A/
HADOOP-14556 as things may not load if aws-sdk isn't on the classpath. It probably lurks in the wasb/abfs support too, but things have worked there because the installations with DT support there have always had correctly set up classpaths.
Fix: do what we did for the FS service loader. Catch failures to instantiate a service provider impl and skip it