GroovyClassLoader addClasspath RegexPattern issue

When adding Groovy Files from the file system to the GroovyClassLoader's classpath grabbed from a default java properties file ("/" instead of "\"))
Then the addClasspath() method uses a simple URL instead of the File URL

This is due to a simple mistake in this mentioned method:

public void addClasspath(final String path) {
....
     if (!URI_PATTERN.matcher(path).matches()) {
          newURI = new File(path).toURI();
     } else {
          newURI = new URI(path);
     }
}

private static final Pattern URI_PATTERN = Pattern.compile("\\p{Alpha}[-+.\\p{Alnum}]*:[^\\\\]*");

The URI_PATTERN which should match "URIs but not Windows filenames" doesn't work as expected.
It matches i.e. C:/xxx/file.ext
This is related to using forward instead of backslashes - which souldn't matter.

This was i.e. NOT the case for Groovy 2.1.3