diff --git a/config/samples/traits/manualscaletrait_definition.yaml b/config/samples/traits/manualscaletrait_definition.yaml
index 942b8426a..a45dbb310 100644
--- a/config/samples/traits/manualscaletrait_definition.yaml
+++ b/config/samples/traits/manualscaletrait_definition.yaml
@@ -2,9 +2,9 @@ apiVersion: core.oam.dev/v1alpha2
 kind: TraitDefinition
 metadata:
   name: manualscalertrait.core.oam.dev
-  annotation:
-    "oam.appengine.info/apiVersion": "core.oam.dev/v1alpha2"
-    "oam.appengine.info/kind": "ManualScalerTrait"
+  annotations:
+    oam.appengine.info/apiVersion: "core.oam.dev/v1alpha2"
+    oam.appengine.info/kind: "ManualScalerTrait"
 spec:
   appliesToWorkloads:
     - core.oam.dev/v1alpha2.ContainerizedWorkload
diff --git a/config/samples/traits/simplerollouttrait_definition.yaml b/config/samples/traits/simplerollouttrait_definition.yaml
index 5500a0b3a..793712483 100644
--- a/config/samples/traits/simplerollouttrait_definition.yaml
+++ b/config/samples/traits/simplerollouttrait_definition.yaml
@@ -2,7 +2,7 @@ apiVersion: core.oam.dev/v1alpha2
 kind: TraitDefinition
 metadata:
   name: simplerollouttraits.extend.oam.dev
-  annotation:
+  annotations:
     "oam.appengine.info/apiVersion": "extend.oam.dev/v1alpha2"
     "oam.appengine.info/kind": "SimpleRolloutTrait"
 spec:
diff --git a/config/samples/workloads/containerizedworkload_definition.yaml b/config/samples/workloads/containerizedworkload_definition.yaml
index eab0eee15..5c14ca538 100644
--- a/config/samples/workloads/containerizedworkload_definition.yaml
+++ b/config/samples/workloads/containerizedworkload_definition.yaml
@@ -2,9 +2,9 @@ apiVersion: core.oam.dev/v1alpha2
 kind: WorkloadDefinition
 metadata:
   name: containerizedworkloads.core.oam.dev
-  annotation:
-    "oam.appengine.info/apiVersion": "core.oam.dev/v1alpha2"
-    "oam.appengine.info/kind": "ContainerizedWorkload"
+  annotations:
+    oam.appengine.info/apiVersion: "core.oam.dev/v1alpha2"
+    oam.appengine.info/kind: "ContainerizedWorkload"
 spec:
   definitionRef:
     name: containerizedworkloads.core.oam.dev
diff --git a/config/samples/workloads/deployment_definition.yaml b/config/samples/workloads/deployment_definition.yaml
index 1263921f5..1c5c70558 100644
--- a/config/samples/workloads/deployment_definition.yaml
+++ b/config/samples/workloads/deployment_definition.yaml
@@ -2,9 +2,9 @@ apiVersion: core.oam.dev/v1alpha2
 kind: WorkloadDefinition
 metadata:
   name: deployments.apps
-  annotation:
-    "oam.appengine.info/apiVersion": "apps/v1"
-    "oam.appengine.info/kind": "Deployment"
+  annotations:
+    oam.appengine.info/apiVersion: "apps/v1"
+    oam.appengine.info/kind: "Deployment"
 spec:
   definitionRef:
     name: deployments.apps