JGroups is no longer part of the supported bits of WFK 2 / Hibernate Search. We could remove the org.hibernate.search.backend.impl.jgroups and the potential dependencies in the code.
and hibernate-search-engine/src/main/resources/META-INF/service/org.hibernate.search.spi.ServiceProvider ?
yes you are correct the ServiceProvider file must be emptied or deleted
We could but it's of no major consequence if we leave it in. If someone tries to select "infinispan" this will raise an exception one way or the other in WFK.