Javadoc
Initially, this method is here only to share the code for "availability check" and for "contains" check.
Unfortunately, the "availability" check cannot be done at RemoteStorage level, since it is completely repository
layout unaware and is able to tell only about the existence of remote server and that the URI on it exists. This
"availability" check will have to be moved upper into repository, since it is aware of "what it holds".
Ultimately, this method will check is the remote server "present" and is responding or not. But nothing more.