A single explicit request for a configuration change.
The requested change is committed to a configuration only when the
execute() method is called. Configuration change
requests are executed asynchronously. This is done to avoid reentrance
problems with objects that are registered as
XConfigurationChangeListener and at the same time make
configuration change requests. When the requests were executed
synchronously then the listeners would be notified of the changes while
their request call has not yet returned.
