Wrong HAL _links are generated in sub type of a schema

[Thomaleh]

Describe the bug

HAL _links field is generated incorrectly for a subtype schema extending a schema that extends a RepresentationModel.

_links:
  type: array
  items:
    $ref: "#/components/schemas/Link"

To Reproduce Steps to reproduce the behavior:

• spring-boot version: 3.5.8 (using spring-boot-starter-hateoas and spring-boot-starter-web)
• springdoc-openapi-starter-webmvc-ui version: 2.8.14

Code Snippet:

import io.swagger.v3.oas.annotations.media.Schema;
import org.springframework.hateoas.RepresentationModel;

@Schema(subTypes = {ExtendedTestDto.class})
public class TestDto extends RepresentationModel<TestDto> {
	private String field;

	public String getField() {
		return field;
	}

	public void setField(String field) {
		this.field = field;
	}
}

import io.swagger.v3.oas.annotations.media.Schema;

@Schema(allOf = {TestDto.class})
public class ExtendedTestDto extends TestDto {
	private String otherField;

	public String getOtherField() {
		return otherField;
	}

	public void setOtherField(String otherField) {
		this.otherField = otherField;
	}
}

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Controller {

	@GetMapping(path = "/hello")
	public ExtendedTestDto hello() {
		return new ExtendedTestDto();
	}
}

Expected behavior

The subtype should not have a _links field at all since that field is already in the schema of TestDto. This worked as expected in springdoc-openapi-starter-webmvc-ui version:2.7.0.

Actual:

ExtendedTestDto:
  allOf:
  - $ref: "#/components/schemas/TestDto"
  - type: object
    properties:
      otherField:
        type: string
      _links:
        type: array
        items:
          $ref: "#/components/schemas/Link"

Expected:

ExtendedTestDto:
  type: object
  allOf:
  - $ref: "#/components/schemas/TestDto"
  - type: object
    properties:
      otherField:
        type: string