Have authenticationConverter use the interface AuthoritiesConverter

[Psynbiotik]

The article says this:

Because of generics type erasure in the JVM and because there could be many Converter beans with different inputs and outputs in an application context, this AuthoritiesConverter interface can be a useful tip for the bean factory when it searches for a Converter<Map<String, Object>, Collection<GrantedAuthority>> bean.

Then it never uses the interface for the authenticationConverter.