Make AttributeNullabilityType enum private

src/app/clusters/door-lock-server/door-lock-server.h

@@ -78,14 +78,6 @@ static constexpr size_t DOOR_LOCK_MAX_USER_NAME_SIZE = 10; /**< Maximum size of
 static constexpr size_t DOOR_LOCK_USER_NAME_BUFFER_SIZE =
     DOOR_LOCK_MAX_USER_NAME_SIZE + 1; /**< Maximum size of the user name string (in bytes). */
 
-enum class AttributeNullabilityType : uint8_t
-{
-    kNullable = 0,
-    /**< Used to indicate if an attribute can be nullable */
-    kNotNullable = 1,
-    /**< Used to indicate if an attribute is not nullable */
-};
-
 struct EmberAfPluginDoorLockCredentialInfo;
 struct EmberAfPluginDoorLockUserInfo;
 
@@ -796,6 +788,15 @@ struct EmberAfPluginDoorLockHolidaySchedule
     OperatingModeEnum operatingMode; /** Operating mode during the schedule. */
 };
 
+/**
+ * @brief Indicates whether an attribute can be nullable or not.
+ */
+enum class AttributeNullabilityType : uint8_t
+{
+    kNullable    = 0, /**< Indicates if an attribute is nullable */
+    kNotNullable = 1, /**< Indicates if an attribute is not nullable */
+};
+
 /**
  * @brief This callback is called when Door Lock cluster needs to access the Week Day schedule in the schedules database.
  *