Operate the commands on the latest conf and return a new conf object
If there are errors in the commands , throw a SolrException. return a null
if no changes are to be made as a result of this edit. It is the responsibility
of the implementation to ensure that the returned config is valid . The framework
does no validation of the data
This method attempts to authenticate the request. Upon a successful authentication, this
must call the next filter in the filter chain and set the user principal of the request,
or else, upon an error or an authentication failure, throw an exception.