A DESCRIPTION OF THE PROBLEM :
The implementation in constructor of File(URI) throws an IllegalArgumentException("URI has an authority component") when using a pathname in UNC notation (e.g. "//nas/root"). The bug is, that the URI authority for schema "file:" is part of the path.
Using File("//nas/root") works as expected.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
File file = new File(new URL("//nas/root").toURI());


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
file is valid
ACTUAL -
IllegalArgumentException("URI has an authority component")

---------- BEGIN SOURCE ----------
File file = new File(new URL("//nas/root").toURI());
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
in File(URI):
        // Check our many preconditions
        if (!uri.isAbsolute())
            throw new IllegalArgumentException("URI is not absolute");
        if (uri.isOpaque())
            throw new IllegalArgumentException("URI is not hierarchical");
        String scheme = uri.getScheme();
        if ((scheme == null) || !scheme.equalsIgnoreCase("file"))
            throw new IllegalArgumentException("URI scheme is not \"file\"");
        /* bug: omit this statement
        if (uri.getRawAuthority() != null)
            throw new IllegalArgumentException("URI has an authority component");
         */
        if (uri.getRawFragment() != null)
            throw new IllegalArgumentException("URI has a fragment component");
        if (uri.getRawQuery() != null)
            throw new IllegalArgumentException("URI has a query component");
        
        // and here the correction
        String uncPath;
        if (uri.getRawAuthority() == null) {
         // the old behaviour
            uncPath = uri.getPath();
            if (uncPath.isEmpty())
                throw new IllegalArgumentException("URI path component is empty");
        }else {
         // the corrected behaviour with an UNC path
         // remember: URI is a file:
         uncPath = "//" + uri.getRawAuthority() + uri.getPath();
        }
       // contiunue the code...

FREQUENCY : always