Add must_exist to alias remove (#4914) (#4931)

Relates: elastic/elasticsearch#58100

Co-authored-by: Russ Cam <[email protected]>

src/Nest/Indices/AliasManagement/Alias/Actions/AliasRemoveOperation.cs

@@ -24,17 +24,25 @@ public class AliasRemoveOperation
  public IEnumerable<string> Aliases { get; set; }
 
  /// <summary>
- /// The index to which to add the alias.
+ /// The index to which to remove the alias.
  /// Multiple indices can be specified with <see cref="Indices"/>
  /// </summary>
  [DataMember(Name ="index")]
  public IndexName Index { get; set; }
 
  /// <summary>
- /// The indices to which to add the alias
+ /// The indices to which to remove the alias
  /// </summary>
  [DataMember(Name = "indices")]
  [JsonFormatter(typeof(IndicesFormatter))]
  public Indices Indices { get; set; }
+
+ /// <summary>
+ /// If <c>true</c>, the alias to remove must exist. Defaults to <c>false</c>.
+ /// <para />
+ /// Valid in Elasticsearch 7.9.0+
+ /// </summary>
+ [DataMember(Name = "must_exist")]
+ public bool? MustExist { get; set; }
  }
 }