Migrate off Fauna

package app;

import com.fauna.client.Fauna;
import com.fauna.client.FaunaClient;
import com.fauna.client.PageIterator;
import com.fauna.exception.FaunaException;
import com.fauna.query.builder.Query;
import com.fauna.types.Document;
import com.fauna.types.Page;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static com.fauna.query.builder.Query.fql;

public class App {

    public static void main(String[] args) {
        try {
            // Route queries to a specific database
            // using the authentication secret in
            // the `FAUNA_SECRET` environment variable.
            FaunaClient client = Fauna.client();

            // Specify the collections to export.
            // You can retrieve a list of user-defined collections
            // using a `Collection.all()` query.
            List<String> collectionsToExport = List.of("Product", "Category");

            // Loop through the collections.
            for (String collectionName : collectionsToExport) {
                // Compose a query using an FQL template string.
                // The query returns a Set containing all documents
                // in the collection.
                Query query = fql("""
                    let collection = Collection(${collectionName})
                    collection.all()
                    """,
                    Map.of("collectionName", collectionName)
                );

                // Run the query and paginate through all results.
                PageIterator<Document> pageIterator = client.paginate(query, Document.class);

                // Initialize a list to collect all documents.
                List<Map<String, Object>> documents = new ArrayList<>();

                // Iterate through the resulting document Set.
                while (pageIterator.hasNext()) {
                    Page<Document> page = pageIterator.next();
                    for (Document document : page.getData()) {
                        // Create a new map to include the document's ID, collection, timestamp, and data.
                        Map<String, Object> docMap = new HashMap<>();
                        docMap.put("id", document.getId());
                        docMap.put("collection", document.getCollection().toString()); // Assuming Module has a proper toString()
                        docMap.put("timestamp", document.getTs().toString());
                        docMap.putAll(document.getData());

                        // Add the map to the documents list.
                        documents.add(docMap);
                    }
                }

                // Convert the 'documents' list to a JSON string.
                ObjectMapper objectMapper = new ObjectMapper();
                objectMapper.enable(SerializationFeature.INDENT_OUTPUT);

                // Write the JSON string to a file named `<collectionName>.json`.
                File outputFile = new File(collectionName + ".json");
                objectMapper.writeValue(outputFile, documents);

                System.out.printf("%s collection data written to %s.json%n", collectionName, collectionName);
            }
        } catch (FaunaException e) {
            System.err.println("Fauna error occurred: " + e.getMessage());
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("Error writing JSON file: " + e.getMessage());
            e.printStackTrace();
        }
    }
}