public class JsonConverter : JsonConverter<Line>
{

    public override Line? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if(typeToConvert != typeof(Line))
            throw new ArgumentException($"Invalid type ({typeToConvert}).", nameof(typeToConvert));
        
        if(reader.TokenType == JsonTokenType.Null)
            return null;

        Line line = new();

        reader.ReadObjectProperties((ref reader, propertyName) =>           <--------
        {
            if(propertyName.SequenceEqual("Keys"u8))                        <--------
            {
                reader.ReadArray((ref reader, index) =>                         <--------
                {
                    line.Add(reader.getByte());
                });
            }
        }
        
        return line;
    }
}

• JsonReadException
• Utf8JsonReader extensions
  • void AssertToken(JsonTokenType tokenType)
  • JsonTokenType ReadOrThrow()
  • JsonTokenType ReadTokenOrThrow(params IEnumerable<JsonTokenType> allowedTokenTypes)
  • byte ReadByte()
  • short ReadInt16()
  • int ReadInt32()
  • long ReadInt64()
  • sbyte ReadSByte()
  • ushort ReadUInt16()
  • uint ReadUInt32()
  • ulong ReadUInt64()
  • float ReadSingle()
  • double ReadDouble()
  • decimal ReadDecimal()
  • bool ReadBoolean()
  • DateTime ReadDateTime()
  • DateTimeOffset ReadDateTimeOffset()
  • Guid ReadGuid()
  • string? ReadString()
  • void ReadObjectProperties(ReadPropertyDelegate readPropertyAction)
  • void ReadObject(ReadPropertyDelegate readPropertyAction)
  • void ReadArrayEntries(ReadArrayEntryDelegate readArrayEntryAction)
  • void ReadArray(ReadArrayEntryDelegate readArrayEntryAction)