Returns an MBeanServerConnection object representing
 a remote MBean server on which operations are performed on behalf of
 the supplied delegation subject. For a given JMXConnector
 and Subject, two successful calls to this method will
 usually return the same MBeanServerConnection object,
 though this is not required.
 For each method in the returned
 MBeanServerConnection, calling the method causes
 the corresponding method to be called in the remote MBean
 server on behalf of the given delegation subject instead of the
 authenticated subject. The value returned by the MBean server
 method is the value returned to the client. If the MBean server
 method produces an Exception, the same
 Exception is seen by the client. If the MBean
 server method, or the attempt to call it, produces an
 Error, the Error is wrapped in a
 JMXServerErrorException, which is seen by the
 client.
        
        
Returns:
    an object that implements the 
MBeanServerConnection
 interface by forwarding its methods to the remote MBean server on behalf
 of a given delegation subject. 
Parameters:
 - 
delegationSubject - the 
Subject on behalf of
 which requests will be performed.  Can be null, in which case
 requests will be performed on behalf of the authenticated
 Subject, if any.
Throws:
  - 
IOException - if a valid 
MBeanServerConnection
 cannot be created, for instance because the connection to the remote
 MBean server has not yet been established (with the {@link #connect(Map)
 connect} method), or it has been closed, or it has broken.