Refresh and reload the Configuration.
This method causes this Configuration object to refresh/reload its
contents in an implementation-dependent manner.
For example, if this Configuration object stores its entries in a file,
calling refresh
may cause the file to be re-read.
The default implementation of this method does nothing.
This method should be overridden if a refresh operation is supported
by the implementation.
Throws:
- SecurityException - if the caller does not have permission
to refresh its Configuration.