According to jax-RS specification all methods of any javax.ws.rs.client.WebTarget implementation that returns a new WebTarget instance (such as path(),queryParam(),resolveTemplates()...) must ensure that :

A snapshot of the present configuration of the current (parent) target instance is taken and is inherited by the newly constructed (child) target instance.
...
Therefore, once a configuration is inherited it is also detached (deep copied)
from its parent configuration and changes to the parent and child configurations are not be visible to each other.

Thanks to what have been done in https://issues.jboss.org/browse/RESTEASY-1345, child configuration is partially detached from its parent in a way that invocations of getClasses(), getInstances(), getContracts(...), getProperties() and getProperty(...) on the child does not reflect parent configurations changes and vice versa.

However those configurations are not yet fully detached from each other since providers registered on parent configuration after child configuration creation are taken into account and used by child request/response processing mechanism (see unit tests added to the PR).