Java code explainers

public final class IbanValidator {
 
    private static final Map<String, Integer> COUNTRY_LENGTHS = Map.ofEntries(
        Map.entry("DE", 22), Map.entry("FR", 27), Map.entry("GB", 22),

@Configuration
@EnableWebSecurity
public class OAuth2SecurityConfig {
 

@RestController
@RequestMapping("/api/reports")
public class OrderReportController {
 

public class SlidingLogRateLimiter {
 
    private final int maxRequests;
    private final long windowMillis;

public final class Slugifier {
 
    private static final Pattern NON_LATIN = Pattern.compile("[^\\w-]");
    private static final Pattern WHITESPACE = Pattern.compile("[\\s]+");

@Repository
public interface OrderRepository extends JpaRepository<Order, Long> {
 
    @Query("""

public record FixedWidthField(String name, int start, int end) {
 
    public String extract(String line) {
        int from = Math.min(start, line.length());

@RestController
@RequestMapping("/api/quotes")
public class QuoteStreamController {
 

@Controller
public class BookController {
 
    private final BookService bookService;

@Component
required to import
public class OutboxEventPublisher {
 

@RestController
@RequestMapping("/api/payments")
public class PaymentController {
 

package com.example.payments.config;
 
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;

public class GitHubUserClient {
 
    private final HttpClient http = HttpClient.newBuilder()
            .connectTimeout(Duration.ofSeconds(10))

public final class AccessLogParser {
 
    private static final Pattern LINE = Pattern.compile(
        "^(?<ip>\\S+) \\S+ \\S+ \\[(?<time>[^\\]]+)\\] "

public class KeysetPaginationRepository {
 
    private final DataSource dataSource;
 

public final class AesGcmCipher {
 
    private static final String TRANSFORMATION = "AES/GCM/NoPadding";
    private static final int GCM_TAG_BITS = 128;

@RestController
@RequestMapping("/api/notifications")
public class NotificationStreamController {
 

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;