Selects the first of a set of Resources (usually files) that exists.
A parameter 'prefix',
<map:parameter src="prefix" value="some/path"/<
may be supplied to the selector instance. This prefix is prepended to all
test expressions before evaluation. The default prefix is '' (empty string),
meaning that all expressions are relative to the current sitemap, unless
explicitly overridden.
NOTE:
Provided resource URI is resolved as Source, relative to the current
sitemap, which differs from behavior of selector in previous versions.
To resolve resource paths relative to the context root, provide prefix
parameter:
<map:parameter name="prefix" value="context://"/<
For example, we could define a ResourceExistsSelector with:
select(String expression,
Map objectModel,
Parameters parameters)
Selectors test pattern against some objects in a Map
model and signals success with the returned boolean value