dotnet-graphql fails to download schema from Hasura

[nloum]

Describe the bug
dotnet-graphql crashes when downloading schema from Hasura. This is because Hasura has directives that don't specify whether they are repeatable or not. See the additional context at the bottom of this bug report, where I fixed the issue (but I don't know if this is the fix you guys want).

To Reproduce
Steps to reproduce the behavior:

1. Create a directory on your local machine
2. Download the following docker-compose.yml file to it:

version: '3'

volumes:
  postgres-data:
  pgadmin:

services:
  postgres:
    image: postgres:13
    restart: always
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U MyApplication"]
      interval: 10s
      timeout: 5s
      retries: 5
    ports:
      - "5432:5432"
    environment:
      POSTGRES_USER: MyApplication
      POSTGRES_PASSWORD: changeme
      POSTGRES_DB: MyApplication
    volumes:
      - postgres-data:/var/lib/postgresql/data
      - ./postgres-backups:/var/lib/pgadmin/storage
  graphql-engine:
    image: hasura/graphql-engine:v2.0.0-alpha.8
    ports:
    - "8080:8080"
    depends_on:
    - postgres
    restart: always
    environment:
      HASURA_GRAPHQL_DATABASE_URL: postgres://MyApplication:changeme@postgres:5432/MyApplication
      ## enable the console served by server
      HASURA_GRAPHQL_ENABLE_CONSOLE: "true" # set to "false" to disable console
      ## enable debugging mode. It is recommended to disable this in production
      HASURA_GRAPHQL_DEV_MODE: "true"
      HASURA_GRAPHQL_ENABLED_LOG_TYPES: startup, http-log, webhook-log, websocket-log, query-log
      ## uncomment next line to set an admin secret
      # HASURA_GRAPHQL_ADMIN_SECRET: myadminsecretkey

3. Run the following commands in that directory:

docker-compose up
dotnet new tool-manifest
dotnet tool install StrawberryShake.Tools --local
dotnet graphql init http://localhost:8080/v1/graphql

4. Notice the following exception displayed by dotnet-graphql:

Download schema started.
Download schema completed in 158 ms
Unhandled exception. System.Text.Json.JsonException: The JSON value could not be converted to System.Boolean. Path: $.data.schema.directives[0].isRepeatable | LineNumber: 0 | BytePositionInLine: 226.
 ---> System.InvalidOperationException: Cannot get the value of a token type 'Null' as a boolean.
   at System.Text.Json.Utf8JsonReader.GetBoolean()
   at System.Text.Json.Serialization.Converters.BooleanConverter.Read(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options)
   at System.Text.Json.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter`2.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, TCollection& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
   --- End of inner exception stack trace ---
   at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& state, Utf8JsonReader& reader, Exception ex)
   at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
   at System.Text.Json.JsonSerializer.ReadCore[TValue](JsonConverter jsonConverter, Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
   at System.Text.Json.JsonSerializer.ReadCore[TValue](JsonReaderState& readerState, Boolean isFinalBlock, ReadOnlySpan`1 buffer, JsonSerializerOptions options, ReadStack& state, JsonConverter converterBase)
   at System.Text.Json.JsonSerializer.ReadAsync[TValue](Stream utf8Json, Type returnType, JsonSerializerOptions options, CancellationToken cancellationToken)
   at HotChocolate.Utilities.Introspection.IntrospectionClient.ExecuteIntrospectionAsync(HttpClient client, HttpQueryRequest request, CancellationToken cancellationToken) in /home/vsts/work/1/s/src/HotChocolate/Utilities/src/Utilities.Introspection/IntrospectionClient.cs:line 144
   at HotChocolate.Utilities.Introspection.IntrospectionClient.DownloadSchemaAsync(HttpClient client, CancellationToken cancellationToken) in /home/vsts/work/1/s/src/HotChocolate/Utilities/src/Utilities.Introspection/IntrospectionClient.cs:line 73
   at HotChocolate.Utilities.Introspection.IntrospectionClient.DownloadSchemaAsync(HttpClient client, Stream stream, CancellationToken cancellationToken) in /home/vsts/work/1/s/src/HotChocolate/Utilities/src/Utilities.Introspection/IntrospectionClient.cs:line 49
   at StrawberryShake.Tools.DefaultFileSystem.WriteToAsync(String fileName, Func`2 write) in /home/vsts/work/1/s/src/StrawberryShake/Tooling/src/dotnet-graphql/DefaultFileSystem.cs:line 81
   at StrawberryShake.Tools.IntrospectionHelper.DownloadSchemaAsync(HttpClient client, IFileSystem fileSystem, IActivity activity, String fileName, CancellationToken cancellationToken) in /home/vsts/work/1/s/src/StrawberryShake/Tooling/src/dotnet-graphql/IntrospectionHelper.cs:line 21
   at StrawberryShake.Tools.InitCommandHandler.DownloadSchemaAsync(InitCommandContext context, CancellationToken cancellationToken) in /home/vsts/work/1/s/src/StrawberryShake/Tooling/src/dotnet-graphql/InitCommandHandler.cs:line 92
   at StrawberryShake.Tools.InitCommandHandler.ExecuteInternalAsync(InitCommandContext context, CancellationToken cancellationToken) in /home/vsts/work/1/s/src/StrawberryShake/Tooling/src/dotnet-graphql/InitCommandHandler.cs:line 64
   at StrawberryShake.Tools.InitCommandHandler.ExecuteAsync(InitCommandArguments arguments, CancellationToken cancellationToken) in /home/vsts/work/1/s/src/StrawberryShake/Tooling/src/dotnet-graphql/InitCommandHandler.cs:line 50
   at McMaster.Extensions.CommandLineUtils.CommandLineApplication.ExecuteAsync(String[] args, CancellationToken cancellationToken)
   at StrawberryShake.Tools.Program.<Main>(String[] args)

Expected behavior
I expected the Hasura schema to be downloaded to schema.graphql

Desktop (please complete the following information):

• OS: Manjaro Linux
• Version: 21.0.2

Additional context
I have a fix for this which basically makes the Directive.IsRepeatable property be nullable, and in IntrospectionDeserializer uses a value of false if IsRepeatable is null. Is that the kind of fix you guys think is appropriate?