Any data that is not a primitive type or Enum is serialized to a JSON or Base64 string before it is transmitted to the plugin. If you serialized your data using a BinaryFormatter, follow the instructions in the Binary Data section. If you did not serialize your data at all, follow the instructions in the JSON Data section.
If you previously used a BinaryFormatter to serialize your objects to a byte array before saving them you can read them by converting them to a Base64 String and then proceeding with your original deserialization procedure using a BinaryFormatter. You may need to trim excess quotes or backslashes added on by the serializer.