import groovy.json.JsonOutput
import groovy.json.JsonSlurper

def jsonSlurper = new JsonSlurper()
def data = jsonSlurper.parse(new URL('https://gitee.com/holate/public-holiday/raw/master/holidays/year/2021.json')) as Map
def map = [:]
data.holiday.each {k, v ->
    map.put(k, v.holiday)
}
println JsonOutput.toJson(map)