CouchDB Replication API

I'm trying to setup a mock source for CouchDB Replication (for testing):

package com.kouchdb.dynamodb_source;

import java.io.IOException;
import java.util.Arrays;

import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.kouchdb.dynamodb_source.ChangesResponse.Result;
import com.kouchdb.dynamodb_source.ChangesResponse.Revision;

import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServletResponse;

@Controller
public class AppController {

private static long startTime = System.currentTimeMillis();

@RequestMapping(value = "/{db}/_changes", method = RequestMethod.GET)
@ResponseBody
public ChangesResponse getChanges(@PathVariable String db,
@RequestParam(defaultValue = "") String feed,
@RequestParam(defaultValue = "") String style,
@RequestParam(defaultValue = "") String since,
@RequestParam(defaultValue = "-1") Integer timeout) {
if(since.equals("0")) {
return new ChangesResponse(Arrays.asList(new Result("seq-1", "id-1",
Arrays.asList(new Revision("1-rev")))), "seq-1", 0);
}
else {
return new ChangesResponse(Arrays.asList(), "seq-1", 0);
}
}

@RequestMapping(value = "/{db}/_local/{id}", method = RequestMethod.GET)
@ResponseBody
public ResponseEntity<String> getLocal(@PathVariable String db,
@PathVariable String id) {
return new ResponseEntity<String>(
"{\"error\":\"not_found\",\"reason\":\"missing\"}",
HttpStatus.NOT_FOUND);
}

@RequestMapping(value = "/{db}/_local/{id}", method = RequestMethod.PUT)
@ResponseBody
public String putLocal(@PathVariable String db,
@PathVariable String id, @RequestBody String body) {
return "{\"ok\":true}";
}

@RequestMapping(value = "/{db}", method = {RequestMethod.GET,
RequestMethod.HEAD})
@ResponseBody
public DbResponse getDatabase(@PathVariable String db) {
return new DbResponse(db, "seq-1", 1, 0);
}

@RequestMapping(value = "/{db}/", method = {RequestMethod.GET,
RequestMethod.HEAD})
@ResponseBody
public DbResponse getDatabaseSlash(@PathVariable String db) {
return this.getDatabase(db);
}

@RequestMapping(value = "/{db}/{id}", method = {RequestMethod.GET})
@ResponseBody
public MultiValueMap<String, Object> getDocument(@PathVariable String db, @PathVariable String id,
@RequestParam boolean revs, @RequestParam String open_revs, @RequestParam boolean latest,
HttpServletResponse response) throws JsonProcessingException, IOException {
response.setContentType(MediaType.MULTIPART_FORM_DATA_VALUE);
MultiValueMap<String, Object> form = new LinkedMultiValueMap<String, Object>();
form.add("json", new DocumentResponse("id-1", "1-rev"));
return form;
}

@RequestMapping(value = "/_session", method = RequestMethod.POST)
@ResponseBody
public SessionResponse startSession(HttpServletResponse response) {
response.addCookie(new Cookie("AuthSession", "dummy"));
return new SessionResponse(true, "dbadmin", Arrays.asList("_admin"));
}

@RequestMapping(value = "/{db}/_ensure_full_commit", method = RequestMethod.POST)
@ResponseBody
public CommitResponse commit(@PathVariable String db) {
return new CommitResponse(true, startTime);
}
}

This is failing with errors as shown in screenshots.

Please do not bid on this project unless you already know the solution. I don't have time for someone to try to solve it from scratch.