If the default server is started with the clustered.xml configuration without any change the following WARN message is shown:

WARN [org.infinispan.configuration.cache.IndexingConfigurationBuilder] (MSC service thread 1-3) ISPN000403: No indexable classes were defined for this indexed cache; switching to autodetection (support for autodetection will be removed in Infinispan 10.0).

Even if the relation to "Infinispan 10.0" does not make sense for the product, the message itself is useless as there are no classes deployed.
So in client server mode the message makes no sense at all.