Alternative server for source or target should be used exclusively if the respective alternative_* parameters are set

Current Situation:
If JADE faces a connection error to the source or the target system then it tries a second connection to an alternative server (if configured to do so). It tries it even though no alternative_source_ or alternative_target_ parameter are set.

Desired Behaviour:
An alternative connection should be used exclusivey if the alternative_* parameters are set.