In a <map:handle-errors>, selects depending on the exception that caused the error.
The configuration of this selector allows to map exception class names to symbolic names
that are used in the <map:when> alternatives.
the "class" is the class name of the exception (which can be any Throwable),
an exception can be given a name, which is used in the <map:when> tests,
an exception can be unrolled, meaning we try to get its cause and then consider this cause for
the exception name
Note that both "name" and "unroll" can be specified. In that case, we first try to unroll the exception,
and if none of the causes has a name, then the "name" attribute is considered.
getSelectorContext(Map objectModel,
Parameters parameters)
Compute the exception type, given the configuration and the exception stored in the object model.
boolean
select(String expression,
Object selectorContext)
Switch Selectors test patterns against a context object
and signal success with the returned boolean value