[core] missingKeyGenerator do no longer exist

packages/mui-base/src/useCompound/useCompoundItem.ts

@@ -11,7 +11,7 @@ export interface UseCompoundItemReturnValue<Key> {
   /**
    * The unique key for the child component.
    * If the id was provided to `useCompoundItem`, this will be the same value.
-   * Otherwise, this will be a value generated by the `missingKeyGenerator`.
+   * Otherwise, this will be a value generated by the `id` function.
    */
   id: Key | undefined;
   /**
@@ -30,10 +30,9 @@ export interface UseCompoundItemReturnValue<Key> {
  *
  * @param id A unique key for the child component. If the `id` is `undefined`, the registration logic will not run (this can sometimes be the case during SSR).
  *   This can be either a value, or a function that generates a value based on already registered siblings' ids.
- * @param itemMetadata Arbitrary metadata to pass to the parent component. This should be a stable reference (e.g. a memoized object), to avoid unnecessary re-registrations.
- * @param missingKeyGenerator A function that generates a unique id for the item.
- *   It is called with the set of the ids of all the items that have already been registered.
+ *   If a functio, it's called with the set of the ids of all the items that have already been registered.
  *   Return `existingKeys.size` if you want to use the index of the new item as the id.
+ * @param itemMetadata Arbitrary metadata to pass to the parent component. This should be a stable reference (e.g. a memoized object), to avoid unnecessary re-registrations.
  *
  * @ignore - internal hook.
  */

packages/mui-base/src/useCompound/useCompoundParent.ts

@@ -4,7 +4,6 @@ import * as React from 'react';
 interface RegisterItemReturnValue<Key> {
   /**
    * The id of the item.
-   * If the `id` was `undefined`, an id from the `missingKeyGenerator` will be used.
    */
   id: Key;
   /**