diff --git a/apis/duck/ABOUT.md b/apis/duck/ABOUT.md
index b223412a0..989769220 100644
--- a/apis/duck/ABOUT.md
+++ b/apis/duck/ABOUT.md
@@ -302,7 +302,11 @@ is used with duck types:
                 ...
         }
         logger := c.Logger.Named("Revisions")
-        impl := controller.NewImpl(c, logger, "Revisions")
+        impl := controller.NewContext(
+          ctx,
+          c,
+          controller.ControllerOptions{WorkQueueName: "Revisions", Logger: logger},
+        )
 
         // Calls to Track create a 30 minute lease before they must be renewed.
         // Coordinate this value with controller resync periods.
diff --git a/apis/duck/v1/source_types.go b/apis/duck/v1/source_types.go
index 2f1afe246..00e699156 100644
--- a/apis/duck/v1/source_types.go
+++ b/apis/duck/v1/source_types.go
@@ -17,6 +17,7 @@ limitations under the License.
 package v1
 
 import (
+	"context"
 	"time"
 
 	corev1 "k8s.io/api/core/v1"
@@ -170,3 +171,45 @@ type SourceList struct {
 
 	Items []Source `json:"items"`
 }
+
+func (s *Source) Validate(ctx context.Context) *apis.FieldError {
+	if s == nil {
+		return nil
+	}
+	return s.Spec.Validate(ctx).ViaField("spec")
+}
+
+func (s *SourceSpec) Validate(ctx context.Context) *apis.FieldError {
+	return s.CloudEventOverrides.Validate(ctx).ViaField("ceOverrides")
+}
+
+func (ceOverrides *CloudEventOverrides) Validate(ctx context.Context) *apis.FieldError {
+	for key := range ceOverrides.Extensions {
+		if err := validateExtensionName(key); err != nil {
+			return err.ViaField("extensions")
+		}
+	}
+	return nil
+}
+
+func validateExtensionName(key string) *apis.FieldError {
+	if key == "" {
+		return apis.ErrInvalidKeyName(
+			key,
+			"",
+			"keys MUST NOT be empty",
+		)
+	}
+
+	for _, c := range key {
+		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9')) {
+			return apis.ErrInvalidKeyName(
+				key,
+				"",
+				"keys are expected to be alphanumeric",
+			)
+		}
+	}
+
+	return nil
+}
diff --git a/apis/duck/v1/source_types_test.go b/apis/duck/v1/source_types_test.go
new file mode 100644
index 000000000..37dfb718c
--- /dev/null
+++ b/apis/duck/v1/source_types_test.go
@@ -0,0 +1,91 @@
+/*
+Copyright 2021 The Knative Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1
+
+import (
+	"context"
+	"testing"
+
+	"knative.dev/pkg/apis"
+)
+
+func TestSourceValidate(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		src  *Source
+		want *apis.FieldError
+	}{{
+		name: "empty source validation",
+		src:  nil,
+		want: nil,
+	}, {
+		name: "empty source ceOverrides extensions validation",
+		src: &Source{Spec: SourceSpec{
+			CloudEventOverrides: &CloudEventOverrides{Extensions: map[string]string{}},
+		}},
+		want: nil,
+	}, {
+		name: "empty extension name error",
+		src: &Source{Spec: SourceSpec{
+			CloudEventOverrides: &CloudEventOverrides{Extensions: map[string]string{"": "test"}},
+		}},
+		want: apis.ErrInvalidKeyName(
+			"",
+			"spec.ceOverrides.extensions",
+			"keys MUST NOT be empty",
+		),
+	}, {
+		name: "long extension key name is valid",
+		src: &Source{Spec: SourceSpec{
+			CloudEventOverrides: &CloudEventOverrides{
+				Extensions: map[string]string{"nameLongerThan20Characters": "test"},
+			},
+		}},
+		want: nil,
+	}, {
+		name: "invalid extension name",
+		src: &Source{Spec: SourceSpec{
+			CloudEventOverrides: &CloudEventOverrides{Extensions: map[string]string{"invalid_name": "test"}},
+		}},
+		want: apis.ErrInvalidKeyName(
+			"invalid_name",
+			"spec.ceOverrides.extensions",
+			"keys are expected to be alphanumeric",
+		),
+	}, {
+		name: "valid extension name",
+		src: &Source{Spec: SourceSpec{
+			CloudEventOverrides: &CloudEventOverrides{
+				Extensions: map[string]string{"validName": "test"},
+			},
+		}},
+		want: nil,
+	}} {
+		t.Run(tt.name, func(t *testing.T) {
+			tt := tt
+			t.Parallel()
+			got := tt.src.Validate(context.TODO())
+			if tt.want != nil && got.Error() != tt.want.Error() {
+				t.Errorf("Unexpected error want:\n%+s\ngot:\n%+s", tt.want, got)
+			}
+
+			if tt.want == nil && got != nil {
+				t.Errorf("Unexpected error want:\nnil\ngot:\n%+s", got)
+			}
+		})
+	}
+}