Can not find ImmutableErrorDetails

Thank you for the work you do, it's very rewarding!
I wanted to implement my own connector using the SDK, but, while reading the source code, I found the following error:
import com.amazonaws.appflow.custom.connector.model.ImmutableErrorDetails.
In this line of code, the class ImmutableErrorDetails is not found. I checked the contents of model/ and found that the file ImmutableErrorDetails.java does not exist.
Is this class removed due to a subsequent code update? (but there is still a lot of ImmutableErrorDetails used in the code) or is it due to some erroneous deletion?

Start by inspecting the model/ directory and the import of ImmutableErrorDetails, then search the repository for its remaining references. Determine whether the missing class is expected to be generated or restored, and confirm the result with the project's available build or test command.

Written by the indexing model from the issue text.