@Override
    public String toString() {
        return "[" + Arrays.stream(MetadataVersion.VERSIONS).map(MetadataVersion::version).collect(
             Collectors.joining(", ")) + "]";
    }
@Test
    public void testMetadataVersionValidator() {
        String str = new MetadataVersionValidator().toString();
        String[] apiVersions = str.substring(1).split(",");
        assertEquals(MetadataVersion.VERSIONS.length, apiVersions.length);
    }