EJB client from EAP 7.0 invokes a bean on EAP 7.1. The bean's remote interface has a compression hint annotation like this:

@CompressionHint(compressRequest = true, compressResponse = true)

The request is compressed, but the response is not.
When invoking the same bean with 7.1 EJB client dependencies (or when 7.0 client is invoking on EAP 7.0), both request and reponse are compressed.