@Override public final int hashCode() {
        return toURI().hashCode();
    }
@Test
    public void testHashCode() throws IOException {
        String parentFolder = "parentFolder";
        File parentFile = tmp.newFolder(parentFolder);
        String child = "child";
        File childFile = new File(parentFile, child);
        VirtualFile vf = new VirtualFileMinimalImplementation(childFile);
        assertThat(vf.hashCode(), is(childFile.toURI().hashCode()));
    }