rspec/rules/S6837/java/rule.adoc

== Why is this an issue?

The Spring framework's `@RestController` annotation is equivalent to using the `@Controller` and `@ResponseBody` annotations together.
As such, it is redundant to add a `@ResponseBody` annotation when the class is already annotated with `@RestController`.

== How to fix it

Remove the `@ResponseBody` annotation from the class or method.

=== Code examples

==== Noncompliant code example

[source,java,diff-id=1,diff-type=noncompliant]
----
@RestController
public class MyController {
  @ResponseBody // Noncompliant, the @RestController annotation already implies @ResponseBody
  @RequestMapping("/hello")
  public String hello() {
    return "Hello World!";
  }
}
----

==== Compliant solution

[source,java,diff-id=1,diff-type=compliant]
----
@RestController
public class MyController {
  @RequestMapping("/hello")
  public String hello() {
    return "Hello World!";
  }
}
----

==== Noncompliant code example

[source,java,diff-id=2,diff-type=noncompliant]
----
@RestController
@ResponseBody // Noncompliant, the @RestController annotation already implies @ResponseBody
public class MyController {
  @RequestMapping("/hello")
  public String hello() {
    return "Hello World!";
  }
}
----

==== Compliant solution

[source,java,diff-id=2,diff-type=compliant]
----
@RestController
public class MyController {
  @RequestMapping("/hello")
  public String hello() {
    return "Hello World!";
  }
}
----

== Resources
=== Articles & blog posts
* Spring Guides - https://spring.io/guides/gs/rest-service/[Building a RESTful Web Service]
* Baeldung - https://www.baeldung.com/spring-controller-vs-restcontroller[The Spring @Controller and @RestController Annotations]
* Baeldung - https://www.baeldung.com/spring-request-response-body[Spring's RequestBody and ResponseBody Annotations]