Configure JsonNullable as simple type for Spring Fox

SpringFoxConfig.java

@Configuration
@EnableSwagger2
public class SpringFoxConfiguration {
    @Bean
    @Primary
    public Docket swaggerSpringfoxApiDocket(List<SwaggerCustomizer> swaggerCustomizers,
                                            ObjectProvider<AlternateTypeRule[]> alternateTypeRules) {
        Docket docket = new Docket(DocumentationType.SWAGGER_2)
            .select()
            .apis(RequestHandlerSelectors.any())
            .paths(PathSelectors.any())
            .build()
            .useDefaultResponseMessages(false)
            .alternateTypeRules(getAlternateTypeRules());

        swaggerCustomizers.forEach(customizer -> customizer.customize(docket));

        Optional.ofNullable(alternateTypeRules.getIfAvailable()).ifPresent(docket::alternateTypeRules);
        return docket;
    }

    private AlternateTypeRule[] getAlternateTypeRules() {
        TypeResolver typeResolver = new TypeResolver();
      
        AlternateTypeRule jsonNullableTypeRule = new AlternateTypeRule(
            typeResolver.resolve(JsonNullable.class, WildcardType.class),
            typeResolver.resolve(WildcardType.class));

        return new AlternateTypeRule[] { jsonNullableTypeRule };
    }
}