Add support for @PageableDefault

[frankruegamer]

Describe the bug
Declaring a Pageable parameter with @PageableDefaults will not change the reported default values for page, size, sort in the OpenAPI definition.

To Reproduce

• Enable pageable support with springdoc-openapi-data-rest or Pageable replacement with SpringDocUtils.
• Add a controller and a method with a pageable paramater like so:

public Page<...> get(@ParameterObject @PageableDefault(size = 5, sort = "name") Pageable pageable) {}

• The generated schema will look like this

[...]
- name: page
  in: query
  description: Zero-based page index (0..N)
  required: false
  schema:
    minimum: 0
    type: integer
    default: "0"
- name: size
  in: query
  description: The size of the page to be returned
  required: false
  schema:
    minimum: 1
    type: integer
    default: "20"
- name: sort
  in: query
  description: 'Sorting criteria in the format: property(,asc|desc). Default
    sort order is ascending. Multiple sort criteria are supported.'
  required: false
  schema:
    type: array
    items:
      type: string
[...]

• calling the controller without specifying pageable parameters will correctly return 5 elements per page

Expected behavior
@PageableDefault should be recognized to change the defaults for Pageable in the schema.

Additional context

• Using Springdoc v1.4.4, Spring Webflux 2.2.1.RELEASE.
• Default of 20 seems to be coming from org.springframework.boot.autoconfigure.data.web.SpringDataWebProperties.Pageable#defaultPageSize.
• Simply adding @PageableDefault without parameters is enough to change the returned elements per page from 20 to 10 (but not in the schema).
• For WebFlux I also had to configure method argument resolvers:

@Configuration
public class AppConfiguration implements WebFluxConfigurer {

	@Override
	public void configureArgumentResolvers(ArgumentResolverConfigurer configurer) {
		configurer.addCustomResolver(
				new ReactiveSortHandlerMethodArgumentResolver(),
				new ReactivePageableHandlerMethodArgumentResolver()
		);
	}

}

[bnasslahsen]

@frankruegamer,

This is not a bug, but a feature request, as is not supported `@PageableDefault.

You have the following workaround, where you don't even need the dependency: springdoc-openapi-data-rest.

@GetMapping("/items/search")
@Parameters({
		@Parameter(name = "pageNumber", description = "page number",
				in = ParameterIn.QUERY, schema = @Schema(type = "integer",  defaultValue = "0")),
		@Parameter(name = "pageSize", description = "page size",
				in = ParameterIn.QUERY, schema = @Schema(type = "integer",  defaultValue = "5")),
		@Parameter(name = "name", description = "sort specification",
				in = ParameterIn.QUERY, schema = @Schema(type = "string"))
})
public List<ItemDTO> showItems(@Parameter(hidden = true) @PageableDefault(size = 5, sort = "name") Pageable pageable) {
	return new ArrayList<ItemDTO>();
}

Meanwhile, the support is now available with the latest snapshot.

The support will be added with the next release v1.4.5;

[frankruegamer]

@bnasslahsen Thanks a lot! This will be very useful.