Easy way to move a selection of items within a list up and down in Groovy

reorder-selection-in-list

import java.util.Collections

//Input
def elements=['a','b','c','d','e']
def selectedIndices=[1,2,3]
boolean isMovingUp=false

println "Initial: ${elements}"
println "Selection: ${selectedIndices.collect{elements[it]}}"
println "Direction: ${isMovingUp?'<':'>'}"

//Offset  + Iteration according to direction
int offset=isMovingUp?-1:1
def iterate=isMovingUp?"each":"reverseEach"
selectedIndices."$iterate"{ selectedIndex ->
    use(Collections){ 
        elements.swap(selectedIndex, selectedIndex + offset) 
    }
}

//Output
println "Final: ${elements}"