fix(health): handle nil lastTransitionTime (#22897)

resource_customizations/k8s.keycloak.org/Keycloak/health.lua

@@ -7,8 +7,18 @@ if obj.status == nil or obj.status.conditions == nil then
 end
 
 -- Sort conditions by lastTransitionTime, from old to new.
+-- Ensure that conditions with nil lastTransitionTime are always sorted after those with non-nil values.
 table.sort(obj.status.conditions, function(a, b)
-  return a.lastTransitionTime < b.lastTransitionTime
+  -- Nil values are considered "less than" non-nil values.
+  -- This means that conditions with nil lastTransitionTime will be sorted to the end.
+  if a.lastTransitionTime == nil then
+    return false
+  elseif b.lastTransitionTime == nil then
+    return true
+  else
+    -- If both have non-nil lastTransitionTime, compare them normally.
+    return a.lastTransitionTime < b.lastTransitionTime
+  end
 end)
 
 for _, condition in ipairs(obj.status.conditions) do

resource_customizations/k8s.keycloak.org/Keycloak/health_test.yaml

@@ -14,4 +14,8 @@ tests:
 - healthStatus:
     status: Degraded
     message: "Has Errors: Waiting for foo/keycloak-1 due to CrashLoopBackOff: back-off 10s"
-  inputPath: testdata/degraded.yaml
+  inputPath: testdata/degraded.yaml
+- healthStatus:
+    status: Healthy
+    message: ""
+  inputPath: testdata/nil_last_transition_time.yaml

resource_customizations/k8s.keycloak.org/Keycloak/testdata/nil_last_transition_time.yaml

@@ -0,0 +1,13 @@
+apiVersion: k8s.keycloak.org/v1alpha1
+kind: Keycloak
+metadata:
+  name: keycloak-23
+  namespace: keycloak
+status:
+  conditions:
+    - type: Ready
+      status: "True"
+      lastTransitionTime: "2025-05-06T12:00:00Z" # Non-nil lastTransitionTime
+    - type: HasErrors
+      status: "False"
+      lastTransitionTime: null # Nil lastTransitionTime