从groovy中的嵌套映射返回一维映射

def flattenMap(map) {
    def result = [:]
    map.each { key, value ->
        if (value instanceof Map) {
            def flattenedMap = flattenMap(value)
            flattenedMap.each { nestedKey, nestedValue ->
                result["${key}.${nestedKey}"] = nestedValue
            }
        } else {
            result[key] = value
        }
    }
    return result
}

def nestedMap = [
    "a": 1,
    "b": [
        "c": 2,
        "d": 3
    ],
    "e": 4
]

def flattenedMap = flattenMap(nestedMap)
println flattenedMap