Component definitions excluded with names starting with x-

[cubahno]

libopenapi excludes component definitions (parameters, headers, schemas, etc.) whose names start with x-, treating them as extensions rather than valid component definitions.

Environment:
libopenapi version: v0.31.2
Go version: 1.25.5

Reproduction:

package main

import (
	"fmt"
	"os"

	"github.com/pb33f/libopenapi"
	"github.com/pb33f/libopenapi/datamodel"
)

func main() {
	data, err := os.ReadFile("spec.yml")
	if err != nil {
		panic(err)
	}

	// Test with default config (ExcludeExtensionRefs: false)
	docConfig := &datamodel.DocumentConfiguration{
		SkipCircularReferenceCheck: true,
	}

	doc, _ := libopenapi.NewDocumentWithConfiguration(data, docConfig)
	model, _ := doc.BuildV3Model()

	fmt.Printf("Parameters count: %d\n", model.Model.Components.Parameters.Len())
	for name := range model.Model.Components.Parameters.FromOldest() {
		fmt.Printf("  - %s\n", name)
	}

	fmt.Printf("Headers count: %d\n", model.Model.Components.Headers.Len())
	for name := range model.Model.Components.Headers.FromOldest() {
		fmt.Printf("  - %s\n", name)
	}

	fmt.Printf("Schemas count: %d\n", model.Model.Components.Schemas.Len())
	for name := range model.Model.Components.Schemas.FromOldest() {
		fmt.Printf("  - %s\n", name)
	}

	fmt.Printf("RequestBodies count: %d\n", model.Model.Components.RequestBodies.Len())
	for name := range model.Model.Components.RequestBodies.FromOldest() {
		fmt.Printf("  - %s\n", name)
	}

	fmt.Printf("Responses count: %d\n", model.Model.Components.Responses.Len())
	for name := range model.Model.Components.Responses.FromOldest() {
		fmt.Printf("  - %s\n", name)
	}
}

spec.yml