Only do modulo when we access the URL list: faster and more secure since it avoids going out of the array bounds.
Added detection of error that could trigger a switch to another producer URL and react to it.
Make things compile properly on Java 6.
Added toString method.
Split logged and unlogged round-robin since a user request will result in a first non-logged request resulting in bunching of users on same producer if there are only 2 nodes. Multithread proofing.
If cooldown period is not strictly positive, use default.
Added specific override of EndpointConfigurationInfo for tests to prevent from trying (and failing) to refresh when the RegistrationInfo requests the WSRP version.