describe TargetRefs conflict-resolution rules in BackendTLSPolicy (#4048)

Signed-off-by: Norwin Schnyder <[email protected]>

Author: snorwin

apis/v1alpha3/backendtlspolicy_types.go

@@ -76,6 +76,23 @@ type BackendTLSPolicySpec struct {
 	//   be unique across all targetRef entries in the BackendTLSPolicy.
 	// * They select different sectionNames in the same target.
 	//
+	//
+	// When more than one BackendTLSPolicy selects the same target and
+	// sectionName, implementations MUST determine precedence using the
+	// following criteria, continuing on ties:
+	//
+	// * The older policy by creation timestamp takes precedence. For
+	//   example, a policy with a creation timestamp of "2021-07-15
+	//   01:02:03" MUST be given precedence over a policy with a
+	//   creation timestamp of "2021-07-15 01:02:04".
+	// * The policy appearing first in alphabetical order by {name}.
+	//   For example, a policy named `bar` is given precedence over a
+	//   policy named `baz`.
+	//
+	// For any BackendTLSPolicy that does not take precedence, the
+	// implementation MUST ensure the `Accepted` Condition is set to
+	// `status: False`, with Reason `Conflicted`.
+	//
 	// Support: Extended for Kubernetes Service
 	//
 	// Support: Implementation-specific for any other resource