diff --git a/dev-guide/api-conventions.md b/dev-guide/api-conventions.md
index 647471845a..20e6bef04e 100644
--- a/dev-guide/api-conventions.md
+++ b/dev-guide/api-conventions.md
@@ -315,7 +315,7 @@ type MyPlatformConfig struct {
   // +unionDiscriminator
   // +kubebuilder:validation:Enum:="AWS";"Azure";"GCP"
   // +kubebuilder:validation:Required
-  PlatformType string `json:"platformType,omitempty"`
+  PlatformType string `json:"platformType"`
 
   // AWS is the AWS configuration.
   // All structures within the union must be optional and pointers.