Java code explainers

@RestController
@RequestMapping("/api/products")
@RequiredArgsConstructor
public class ProductBatchController {

public class TimedFetchService {
 
    private final ExecutorService executor = Executors.newFixedThreadPool(8);
    private final HttpClient httpClient = HttpClient.newHttpClient();

@Component
public class RefreshTokenSuccessHandler implements AuthenticationSuccessHandler {
 
    private final RefreshTokenService refreshTokenService;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.module.SimpleModule;

@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class TenantResolutionFilter extends OncePerRequestFilter {
 

@Repository
public interface SubscriptionRepository extends JpaRepository<Subscription, Long> {
 
    @Modifying(clearAutomatically = true, flushAutomatically = true)

package com.example.uploads.config;
 
import jakarta.servlet.MultipartConfigElement;
import org.springframework.boot.web.servlet.MultipartConfigFactory;

public final class Levenshtein {
 
    private Levenshtein() {
    }

package com.example.lb;
 
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

public interface GitHubClient {
 
    @GetExchange("/users/{username}")
    GitHubUser getUser(@PathVariable String username);

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/api/products")
public class ProductSearchController {
 

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Map;
 

@Entity
@Table(name = "orders")
@SQLDelete(sql = "UPDATE orders SET deleted = true, deleted_at = now() WHERE id = ?")
@Where(clause = "deleted = false")

@GetMapping("/files/{id}")
public ResponseEntity<StreamingResponseBody> download(
        @PathVariable String id,
        @RequestHeader(value = HttpHeaders.RANGE, required = false) String rangeHeader) throws IOException {

public List<int[]> merge(int[][] intervals) {
    if (intervals.length == 0) {
        return new ArrayList<>();
    }

@Configuration
public class UserImportJobConfig {
 
    @Bean

public final class BomAwareReader {
 
    private static final char UTF8_BOM = '\uFEFF';