max_score and _score are required (and can be null) (#1144)

* max_score and _score are required (and can be null)

* Better with "make contrib"

---------

Co-authored-by: Quentin Pradet <quentin.pradet@elastic.co>

Author: swallez

output/schema/schema.json

@@ -44,7 +44,7 @@ export class Hit<TDocument> {
    * on a search request. Otherwise the field is always present on hits.
    */
   _id?: Id
-  _score?: double | null
+  _score: double | null
   _explanation?: Explanation
   fields?: Dictionary<string, UserDefinedValue>
   highlight?: Dictionary<string, string[]>
@@ -69,7 +69,7 @@ export class HitsMetadata<T> {
   total?: TotalHits | long
   hits: Hit<T>[]
 
-  max_score?: double | null
+  max_score: double | null
 }
 
 export class HitMetadata<TDocument> {