code: @Pure
  	@SuppressWarnings("checkstyle:magicnumber")
  	private static String extractLocalPath(String filename) {
  		if (filename == null) {
  			return null;
  		}
  		final int max = Math.min(FILE_PREFIX.length, filename.length());
  		final int inner = max - 2;
  		if (inner <= 0) {
  			return filename;
  		}
  		boolean foundInner = false;
  		boolean foundFull = false;
  		for (int i = 0; i < max; ++i) {
  			final char c = Character.toLowerCase(filename.charAt(i));
  			if (FILE_PREFIX[i] != c) {
  				foundFull = false;
  				foundInner = i >= inner;
  				break;
  			}
  			foundFull = true;
  		}
  		String fn;
  		if (foundFull) {
  			fn = filename.substring(FILE_PREFIX.length);
  		} else if (foundInner) {
  			fn = filename.substring(inner);
  		} else {
  			fn = filename;
  		}
  		if (Pattern.matches("^(" + Pattern.quote(URL_PATH_SEPARATOR) + "|" //$NON-NLS-1$ //$NON-NLS-2$
  				+ Pattern.quote(WINDOWS_SEPARATOR_STRING) + ")[a-zA-Z][:|].*$", fn)) { //$NON-NLS-1$
  			fn = fn.substring(1);
  		}
  		return fn;
  	}
docs: Test if the given filename is a local filename and extract
  the path component.
  
  @param filename the filename.
  @return the path.