我想在build之前，clean项目，再计算时间，但是如何调用clean这个task呢

//task taskTime {
    def startBulidTime, endBuildTime
    this.afterEvaluate { Project project ->
        def cleanBuild =  project.tasks.getByName('clean')

        def preBuildTask = project.tasks.getByName('preBuild')
        preBuildTask.doFirst {
            dependsOn this.tasks.findByName('clean')
            startBulidTime = System.currentTimeMillis()
            println 'the start time is:' + startBulidTime
        }
        def buildTask = project.tasks.getByName('build')
        buildTask.doLast {
            endBuildTime = System.currentTimeMillis()
            println "the build time is: ${endBuildTime - startBulidTime}"
        }
    }
//}