如何在Springfox的Swagger 2中为字符串请求体定制模型？

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import io.swagger.annotations.ApiParam;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.schema.ModelRef;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;

@Configuration
@EnableSwagger2
public class SwaggerConfig {

    @Bean
    public Docket api() {
        return new Docket(DocumentationType.SWAGGER_2)
                .select()
                .apis(RequestHandlerSelectors.basePackage("com.example.controller"))
                .paths(PathSelectors.any())
                .build()
                .apiInfo(apiInfo())
                .directModelSubstitute(String.class, CustomModel.class);
    }

    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("API Documentation")
                .description("API Documentation for Springfox Swagger 2")
                .version("1.0")
                .build();
    }

    @ApiModel(value = "CustomModel", description = "Custom model for string request body")
    public class CustomModel {
        @ApiModelProperty(value = "String property", example = "example")
        private String property;

        public String getProperty() {
            return property;
        }

        public void setProperty(String property) {
            this.property = property;
        }
    }

    public class ExampleController {

        public void exampleMethod(@ApiParam(value = "String request body", required = true)
                                  @RequestBody CustomModel requestBody) {
            // Method implementation
        }
    }
}