https://learn.microsoft.com/ja-jp/dotnet/api/azure.search.documents.indexes.models.searchfield.isfilterable?view=azure-dotnet
SearchField.IsFilterable Property (Azure.Search.Documents.Indexes.Models) - Azure for .NET...
Gets or sets a value indicating whether the field can be referenced in $filter queries. The default is null. This property must be null for complex fields, but...
azure searchpropertydocumentsindexesmodels