ImageReference should support tag and digest

[briandealwis]

According to the Docker spec, it's ok to have a reference with both a tag and a digest such as ubuntu:latest@sha256:868fd30a0e47b8d8ac485df174795b5e2fe8a6c8f056cc707b232d65b8a1ab68

See also: google/go-containerregistry#351

The following test for ImageReferenceTest fails

  @Test
  public void testParse_tagAndDigest() throws InvalidImageReferenceException {
    String imageReferenceString =
        "ubuntu:latest@sha256:868fd30a0e47b8d8ac485df174795b5e2fe8a6c8f056cc707b232d65b8a1ab68";
    ImageReference imageReference = ImageReference.parse(imageReferenceString);

    Assert.assertEquals("registry.hub.docker.com", imageReference.getRegistry());
    Assert.assertEquals("ubuntu", imageReference.getRepository());
    Assert.assertEquals("latest", imageReference.getTag());
    Assert.assertEquals(
        "sha256:868fd30a0e47b8d8ac485df174795b5e2fe8a6c8f056cc707b232d65b8a1ab68",
        imageReference.getTag());
    Assert.assertTrue(imageReference.isTagDigest());
  }

[TadCordle]

@MaartenMoens @jonahgeorge @jhult We've released v2.2.0, which support image references with both a tag and digest.

[chanseokoh]

Note when using both a tag and a digest (for a base image), the tag is purely for documentation. The digest will determine the image (manifest/manifest list).

For the target image, I think it doesn't make sense to put a digest; you shouldn't do it.