Bundle validation will not fail if default channel is not provided

Default channel annotation is now optional. It is only needed if
there is an intention to update default channel in the index.
As a result, bundle validation will allow default channel annotation
to be missing.

Signed-off-by: Vu Dinh <[email protected]>

Author: dinhxuanvu

pkg/lib/bundle/testdata/validate/invalid_annotations_bundle/metadata/annotations.yaml

@@ -1,5 +1,4 @@
 annotations:
-  operators.operatorframework.io.bundle.channel.default.v1: stable
   operators.operatorframework.io.bundle.channels.v1: stable,beta
   operators.operatorframework.io.bundle.manifests.v1: manifests/
   operators.operatorframework.io.bundle.mediatype.v1: registry+v2

pkg/lib/bundle/validate.go

@@ -207,7 +207,7 @@ func validateAnnotations(mediaType string, fileAnnotations *AnnotationMetadata)
 				validationErrors = append(validationErrors, aErr)
 			}
 		case ChannelDefaultLabel:
-			if val == "" {
+			if ok && val == "" {
 				aErr := fmt.Errorf("Expecting annotation %q to have non-empty value", label)
 				validationErrors = append(validationErrors, aErr)
 			}