11 Must‑Know Spring Boot 3.5 Features with Ready‑to‑Use Code Samples

Spring Boot 3.5 introduces many new features. Below are eleven of the most useful enhancements, each accompanied by a brief description and example code.

1. Strict .enabled configuration property

The .enabled property now only accepts true or false , making the behavior consistent across the framework.

2. Renamed TaskExecutor bean

Spring Boot no longer creates a taskExecutor bean; only applicationTaskExecutor is provided. If existing code references the old name, add an alias via a BeanFactoryPostProcessor :

<code>@Configuration
public class AppConfig {
  @Bean
  static BeanFactoryPostProcessor taskExecutorAlias() {
    return beanFactory -> beanFactory.registerAlias(
      "applicationTaskExecutor", "taskExecutor");
  }
}
</code>

3. Redis configuration

When spring.data.redis.url is set, the database is derived from the URL (default 0 if omitted). The separate spring.data.redis.database property is ignored.

<code>spring:
  data:
    redis:
      url: redis://user:[email protected]:6379/8
      # database: 2   <-- ignored, URL specifies 8
</code>

4. Annotation‑based Servlet and Filter registration

Two new annotations replace the traditional ServletRegistrationBean and FilterRegistrationBean :

@ServletRegistration – registers a Servlet

@FilterRegistration – registers a Filter

<code>@Bean
@FilterRegistration(name = "my-filter", urlPatterns = "/api/*", order = 0)
MyFilter myFilter() {
  return new MyFilter();
}
</code>

5. Loading multiple properties from a single environment variable

Define a multi‑line variable in PowerShell and import it with the env: prefix:

<code>PS C:\Users\Administrator> $appsetting = @"
>> pack.title=Pack
>> pack.version=1.0.0
> "@
PS C:\Users\Administrator> [System.Environment]::SetEnvironmentVariable("APP_PACK", $appsetting, "User")
</code>

In application.yml :

<code>spring:
  config:
    import:
      - "env:APP_PACK"
</code>

Access the values with @Value :

<code>@Component
public class EnvProperties implements CommandLineRunner {
  @Value("${pack.title}")
  private String title;
  @Value("${pack.version}")
  private String version;
  @Override
  public void run(String... args) {
    System.err.printf("title = %s, version = %s%n", title, version);
  }
}
</code>

6. Customizable structured‑log stacktrace

Properties under logging.structured.json.stacktrace let you control stacktrace output, e.g. root order, max length, frame depth, inclusion of common frames, and hash inclusion.

root – first or last

max-length – maximum characters

max-throwable-depth – maximum frames per throwable

include-common-frames – true/false

include-hashes – true/false

<code>logging:
  structured:
    json:
      stacktrace:
        include-hashes: true
</code>

7. ClientHttpConnector builder and properties

WebClient can now be globally configured via properties for connector type, timeouts, and redirect behavior:

<code>spring:
  http:
    reactiveclient:
      settings:
        connector: jetty
        connect-timeout: 2s
        read-timeout: 1s
        redirects: dont-follow
</code>

8. TaskDecorator for scheduled tasks

If a TaskDecorator bean exists, it is applied to the auto‑configured taskScheduler , ThreadPoolTaskSchedulerBuilder , and SimpleAsyncTaskSchedulerBuilder beans.

<code>@Configuration
@EnableScheduling
public class TaskConfig {
  @Bean
  TaskDecorator taskDecorator() {
    return runnable -> () -> {
      System.err.println("Task decorated");
      runnable.run();
    };
  }
}
</code>

9. Custom AsyncTaskExecutor bean

When an Executor bean is present, Spring Boot still auto‑configures an AsyncTaskExecutor . To force usage of a custom executor, set spring.task.execution.mode=force and define the bean:

<code>@Configuration
@EnableAsync
public class AsyncConfig {
  @Bean
  Executor executor() {
    ThreadPoolExecutor executor = new ThreadPoolExecutor(
      5, 5, 60, TimeUnit.SECONDS,
      new ArrayBlockingQueue<>(100),
      new ThreadFactory() {
        private final AtomicInteger c = new AtomicInteger();
        @Override
        public Thread newThread(Runnable r) {
          return new Thread(r, "pack-" + c.incrementAndGet());
        }
      });
    return executor;
  }
}
</code>

<code>spring:
  task:
    execution:
      mode: force
</code>

10. Automatic bootstrapExecutor configuration

If no bootstrapExecutor bean exists, Spring Boot creates one automatically, provided an applicationTaskExecutor bean is present. Example:

<code>@Bean(bootstrap = Bootstrap.BACKGROUND)
Person person() {
  System.err.printf("%s - person bean create%n", Thread.currentThread().getName());
  return new Person();
}
</code>

11. Actuator "heapdump" endpoint security

The default access for the heapdump actuator endpoint is now NONE . To expose it, configure both exposure and access:

<code>management:
  endpoints:
    web:
      exposure:
        include: heapdump
  endpoint:
    heapdump:
      access: unrestricted
</code>

These changes help prevent accidental leakage of sensitive heap data while still allowing intentional use.