IllegalArgumentException: HttpEntity parameter 'null' [SPR-14799]

[spring-projects-issues]

David Zhu opened SPR-14799 and commented

This is probably related to #16892.

We are returning a DeferredResult<?>, with ? always being ResponseEntity<?>

If we change the signature to DeferredResult<ResponseEntity<?>> the error does not occur.

---

Affects: 4.3.2

Issue Links:

• HttpEntity parameter 'null' in method (regression) [SPR-12287] #16892 HttpEntity parameter 'null' in method (regression)

[spring-projects-issues]

Rossen Stoyanchev commented

I tried the following and can't make it happen.

  @GetMapping("/foo")
  public DeferredResult<?> foo() {
    final DeferredResult<Object> result = new DeferredResult<Object>();

    new Thread(new Runnable() {

      @Override
      public void run() {
        try {
          Thread.sleep(3000);
        }
        catch (InterruptedException ex) {
          ex.printStackTrace();
        }
        result.setResult(ResponseEntity.ok("foo"));
      }
    }).start();

    return result;
  }

[spring-projects-issues]

David Zhu commented

Hello Rossen,

Thanks for taking a look at this.

Try

DeferredResult<?> r = new DeferredResult<?>();
r.setResult(new ResponseEntity(HttpStatus.NOT_MODIFIED));
return r;

[spring-projects-issues]

Rossen Stoyanchev commented

Okay that does it.

So in the regular ResponseEntity<?> return value type case we can check the return value or at least find the wildcard from the generic type if there is no body. However with DeferredResult<?> and with no body the generic type checks reach a situation that is not expected and raise an IllegalStateException:

java.lang.IllegalArgumentException: HttpEntity parameter 'null' in method public org.springframework.web.context.request.async.DeferredResult org.springframework.issues.config.TestController.foo() is not parameterized
	at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.getHttpEntityType(HttpEntityMethodProcessor.java:150)
	at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.getReturnValueType(HttpEntityMethodProcessor.java:279)
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:179)
	at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:198)

I suppose we can relax this to return Object.class and let the message conversion process work itself out from there. After all at this point we do know that it is a ResponseEntity but we just can't figure out the body type. And in this case there is not even a body.

[spring-projects-issues]

Rossen Stoyanchev commented

A fix is now available in 4.3.x and master.