Gradle plugin workaround

build.gradle

/* Swagger (https://www.jcore.com/2017/05/22/automatically-generating-api-using-swagger-and-gradle/)*/
import io.swagger.codegen.config.CodegenConfigurator
import io.swagger.codegen.DefaultGenerator

def swaggerTargetFolder = 'build/generated-sources'

def generateFilesFromSwagger(swaggerSourceFile, packageName, swaggerTargetFolder) {
    def config = new CodegenConfigurator()
    config.setInputSpec("$swaggerSourceFile")
    config.setOutputDir("$projectDir")
    config.setLang('spring')
    config.setAdditionalProperties([
            'interfaceOnly' : 'true',
            'apiPackage'    : packageName,
            'modelPackage'  : packageName,
            'sourceFolder'  : swaggerTargetFolder,
            'dateLibrary'   : 'java8'
    ])
    new DefaultGenerator().opts(config.toClientOptInput()).generate()
}

task swagger2java {
    doLast {
        // Order
        generateFilesFromSwagger("file:///$projectDir/src/main/resources/swagger-spec/order.json", 'org.entur.order', swaggerTargetFolder)

        // Payment
        generateFilesFromSwagger("file:///$projectDir/src/main/resources/swagger-spec/payment.json", 'org.entur.payment', swaggerTargetFolder)

        // Offers
        // generateFilesFromSwagger("file:///$projectDir/src/main/resources/swagger-spec/offers.json", 'org.entur.offers', swaggerTargetFolder)
    }
}

// Supporting gradle clean
clean.doFirst {
    delete("${projectDir}/$swaggerTargetFolder")
}

swagger2java.dependsOn wsdl2java // NB! wsdl2java cleans generated sources directory, must happen before swagger gen
compileJava.dependsOn swagger2java

Thanks for posting this configuration, it is what I wanted to achieve. However, it is creating he following error when I run Gradle build:

Could not get unknown property 'clean' for root project 'springboot-service-stencil' of type org.gradle.api.Project.

What I am missing here and why it doesn't recognize 'clean' ?