Swagger plugin for dynamic allowed values, implementing ExpandedParameterBuilderPlugin

DynamicExpandedParameterBuilder.java

package mydomain.swagger;

import mydomain.repo.AttributeMetadataRepo;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.Optional;
import com.google.common.base.Strings;
import io.swagger.annotations.ApiModelProperty;
import io.swagger.annotations.ApiParam;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import springfox.documentation.service.AllowableValues;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spi.service.ExpandedParameterBuilderPlugin;
import springfox.documentation.spi.service.contexts.ParameterExpansionContext;
import springfox.documentation.spring.web.DescriptionResolver;
import springfox.documentation.swagger.annotations.Annotations;
import springfox.documentation.swagger.common.SwaggerPluginSupport;
import springfox.documentation.swagger.schema.ApiModelProperties;
import java.lang.reflect.Field;

@Component
@Order(SwaggerPluginSupport.SWAGGER_PLUGIN_ORDER + 1)
public class DynamicExpandedParameterBuilder implements ExpandedParameterBuilderPlugin {
    private final DescriptionResolver descriptions;
    private final AttributeMetadataRepo attributeMetadataRepo;
    private final ObjectMapper mapper;

    @Autowired
    public DynamicExpandedParameterBuilder(DescriptionResolver descriptions,
                                           AttributeMetadataRepo attributeMetadataRepo, ObjectMapper mapper) {
        this.descriptions = descriptions;
        this.attributeMetadataRepo = attributeMetadataRepo;
        this.mapper = mapper;
    }

    public void apply(ParameterExpansionContext context) {
        Optional<ApiParam> apiParamOptional =
                Annotations.findApiParamAnnotation(context.getField().getRawMember());
        if (apiParamOptional.isPresent()) {
            this.fromApiParam(context, apiParamOptional.get());
        }

        Optional<ApiModelProperty> apiModelPropertyOptional =
                ApiModelProperties.findApiModePropertyAnnotation(context.getField().getRawMember());
        if (apiModelPropertyOptional.isPresent()) {
            this.fromApiModelProperty(context, apiModelPropertyOptional.get());
        }
    }

    public boolean supports(DocumentationType delimiter) {
        return SwaggerPluginSupport.pluginDoesApply(delimiter);
    }

    private void fromApiParam(ParameterExpansionContext context, ApiParam apiParam) {
        String allowableProperty = Strings.emptyToNull(apiParam.allowableValues());
        if ("dynamic[whatever]".equals(allowableProperty)) {
            AllowableValues allowable = this.allowableValues(Optional.fromNullable(allowableProperty),
                    context.getField().getRawMember());
            context.getParameterBuilder().description(this.descriptions.resolve(apiParam.value()))
                    .defaultValue(apiParam.defaultValue()).required(apiParam.required())
                    .allowMultiple(apiParam.allowMultiple()).allowableValues(allowable)
                    .parameterAccess(apiParam.access()).hidden(apiParam.hidden()).build();
        }
    }

    private void fromApiModelProperty(ParameterExpansionContext context, ApiModelProperty apiModelProperty) {
        String allowableProperty = Strings.emptyToNull(apiModelProperty.allowableValues());
        if ("dynamic[whatever]".equals(allowableProperty)) {
            AllowableValues allowable = this.allowableValues(Optional.fromNullable(allowableProperty),
                    context.getField().getRawMember());
            context.getParameterBuilder().description(this.descriptions.resolve(apiModelProperty.value()))
                    .required(apiModelProperty.required()).allowableValues(allowable)
                    .parameterAccess(apiModelProperty.access()).hidden(apiModelProperty.hidden()).build();
        }
    }

    private AllowableValues allowableValues(Optional<String> optionalAllowable, Field field) {
        DynamicAllowableValues allowableValues =
                new DynamicAllowableValues(attributeMetadataRepo);
        return allowableValues;
    }
}