Inidcate unresolved imports #258
Description
Is your feature request related to a problem? Please describe.
Some XPath expressions require that referenced classes are on the classpath (e.g. matchesSig). It may not be obvious why is the rule not working.
Describe the solution you'd like
Visually indicate (warning triangle in th gutter? or maybe just underline?) imports that could not be found on the current classpath.
Describe alternatives you've considered
Indicate all unresolved symbols: might be too noisy.
Additional context
Comes from pmd/pmd#6113