Java code explainers

public final class HmacJwt {
 
    private static final ObjectMapper MAPPER = new ObjectMapper();
    private static final Base64.Encoder ENCODER = Base64.getUrlEncoder().withoutPadding();

public final class MultipartParser {
 
    public record FilePart(String name, String filename, String contentType, byte[] content) {}
 

@AutoConfiguration
@EnableConfigurationProperties(RateLimiterProperties.class)
@ConditionalOnClass(RateLimiter.class)
public class RateLimiterAutoConfiguration {

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Currency;
 

public class RequestCoalescer<K, V> {
 
    private final ConcurrentHashMap<K, CompletableFuture<V>> inFlight = new ConcurrentHashMap<>();
    private final Function<K, V> loader;

public final class NaturalOrderComparator implements Comparator<String> {
 
    public static final NaturalOrderComparator INSTANCE = new NaturalOrderComparator();
 

package com.example.validation;
 
import java.util.List;
import java.util.stream.Collectors;

public URI buildSearchUri(String query, int page, int size, List<String> tags) {
    UriComponentsBuilder builder = UriComponentsBuilder
            .fromUriString("https://api.example.com")
            .path("/v2/products/search")

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {
 

@Configuration
@EnableRedisHttpSession(namespace = "myapp:sessions", maxInactiveIntervalInSeconds = 1800, flushMode = FlushMode.IMMEDIATE)
public class SessionConfig {
 

public List<User> findUsersByEmailDomain(String domain, int minAge) {
    String sql = """
        SELECT id, username, email, age, created_at
        FROM users

@Configuration
@EnableBatchProcessing
public class CustomerImportJobConfig {
 

@Configuration
@EnableWebSecurity
public class ResourceServerConfig {
 

@Configuration
public class OrderConsumerConfig {
 
    @Bean

@Configuration
@EnableKafka
public class KafkaErrorHandlingConfig {
 

@Controller
@RequestMapping("/employees")
public class EmployeeController {
 

package com.example.config.condition;
 
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;

public List<OrderSummary> streamRecentOrders(LocalDateTime since, Consumer<OrderSummary> handler) {
    String sql = """
        SELECT id, customer_id, total_cents, status, created_at
        FROM orders