Get a map's keys in a Jenkinsfile's Groovy sandbox

Jenkinsfile.get_keys

@NonCPS
def getKeys(map) {
    def keylist = []
    for (def entry in map) {
        // For converting map into list:
        // // keylist.add(new java.util.AbstractMap.SimpleImmutableEntry(entry.key, entry.value))
        keylist.add(entry.key)
    }
    keylist
}

def test_hash() {
    util1([name: 'abc', jName: 'jabc', 'gName': 'gabc'])
}
def util1(the_datums) {
    def data_keys = getKeys(the_datums)
    // // or just
    // def data_keys = the_datums.keySet() as String[]
    for (int i = 0; i < data_keys.size(); i++) {
        echo "i ${i}"
        echo "  key ${data_keys[i]}"
        echo "  the_datums[data_keys[i]] ${the_datums[data_keys[i]]}."
    }
}

stage('overall') { node() { timeout(time: 11, unit: 'MINUTES') {
    test_hash()
} } }

//