Common functionality and various exception used by all other packages.
This package defines the base classes for (almost) all exceptions thrown by X-Application.
XException is the base class for checked exceptions and XRuntimeException
is the base class for unchecked exceptions. Both classes support nested exceptions, which is realized
by implementing ExceptionWrapper interface. XException is thrown to indicate an error
situation like database problems, whereas XRuntimeException is thrown to indicate a
bug within X-Applications (e.g. assertion or precondition failures).