配置流水线时，配置了参数，如何在jenkinsfile中覆盖参数

配置流水线时，配置了参数，如何在jenkinsfile中覆盖参数的值？
如下图，我在流水线中配置了fullTime参数，默认值为11111111。

如何在jenkinsfile中覆盖该参数的值呢？

node('openjdk8') {
    def date = new Date()
    def time = date.format('yyyyMMddHHmmss')
    def msec = System.currentTimeMillis()
    
    if (fullTime == "11111111"){
        fullTime = "${time}" + "${msec}"
        echo "${fullTime}"
    }
    
    stage('test') {
        echo "${fullTime}"
    }
}

输出结果中：

2022-04-08 13:45:11.199 | . [Pipeline] {
2022-04-08 13:45:11.224 | . [Pipeline] echo
2022-04-08 13:45:11.230 | . 202204080545111649396711212
2022-04-08 13:45:11.248 | . [Pipeline] stage
2022-04-08 13:45:11.253 | . [Pipeline] { (test)
2022-04-08 13:45:11.273 | . [Pipeline] echo
2022-04-08 13:45:11.276 | . 202204080545111649396711212
2022-04-08 13:45:11.279 | . [Pipeline] }
2022-04-08 13:45:11.291 | . [Pipeline] // stage
2022-04-08 13:45:11.298 | . [Pipeline] }
2022-04-08 13:45:11.313 | . [Pipeline] // node
2022-04-08 13:45:11.323 | . [Pipeline] End of Pipeline
2022-04-08 13:45:11.356 | . Finished: SUCCESS

但是，如果使用下面的jenkinsfile再次定义fullTime，此时jenkinsfile中定义的fullTime作用范围只在if结构内，所以输出仍为11111111。

node('openjdk8') {
    def date = new Date()
    def time = date.format('yyyyMMddHHmmss')
    def msec = System.currentTimeMillis()
    
    if (fullTime == "11111111"){
        def fullTime = "${time}" + "${msec}"
        echo "${fullTime}"
    }
    
    stage('test') {
        echo "${fullTime}"            //输出结果为11111111
    }
}