@NotEmpty is being ignored in 2.8.6 and does not create required attribute

[adgan]

Describe the bug

After updating to version 2.8.6 of [Framework/Library Name], the @NotEmpty annotation on request DTOs no longer generates the required attribute in the OpenAPI file. This behavior worked as expected in the previous version 2.8.5.

To Reproduce
Steps to reproduce the behavior:

1. using @NotEmpty
2. generating OpenAPI yml file
3. looking at the required list

• What version of spring-boot you are using?
  3.4.4
• What modules and versions of springdoc-openapi are you using?
  springdoc-openapi-starter-webmvc-ui @ 2.8.6
• What is the actual and the expected result using OpenAPI Description (yml or json)? yml
• Provide with a sample code (HelloController) or Test that reproduces the problem

public class ExampleRequestDto {
  @Schema(
      name = „test“,
      description = „test“,
      example = „test“,
  )
  @NotEmpty
  private final String test;
}

Expected behavior

Sample code should add a

      required:
      - test

[bnasslahsen]

@adgan,

This looks to be a regression in swagger-core v2.2.29 and there is an existing issue for it: swagger-api/swagger-core#4862.

As a workaround, you can downgrade the swagger-core version to 2.2.28, until this is fixed.

	<dependency>
		<groupId>org.springdoc</groupId>
		<artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
		<version>2.8.6</version>
		<exclusions>
			<exclusion>
				<groupId>io.swagger.core.v3</groupId>
				<artifactId>swagger-core-jakarta</artifactId>
			</exclusion>
		</exclusions>
	</dependency>
	<dependency>
		<groupId>io.swagger.core.v3</groupId>
		<artifactId>swagger-core-jakarta</artifactId>
		<version>2.2.28</version>
	</dependency>

[adgan]

Hey @bnasslahsen,

Thanks for the info! I also found the workaround to add requiredMode = Schema.RequiredMode.REQUIRED to the @Schema to include it in the OpenAPI file.

[ksiczek]

And for Gradle aficionados:

dependencies {

    constraints {
        implementation("io.swagger.core.v3:swagger-core-jakarta") {
            version {
                strictly("2.2.28")
            }
            because("NotEmpty not treated as required https://github.com/swagger-api/swagger-core/issues/4862")
        }
    }
...
}

[MinSang22Kim]

I also encountered the same issue in a Gradle environment.
Downgrading swagger-core-jakarta to version 2.2.28, as suggested above, worked as a temporary workaround for now.
Thanks for the helpful feedback!

[aconrad]

I can confirm that, as a client / consumer of the open api spec in JSON format, "required" fields aren't honored as they used to after upgrading from 2.8.5 to 2.8.6. We annotate required fields with javax.validation.constraints.NotNull;.

Here is a sample generated JSON diff from 2.8.5 to 2.8.6:

             ],
             "type": "string"
           }
-        },
-        "required": [
-          "make",
-          "model"
-        ]
+        }
       },
       "Phone": {
         "properties": {