Extensions/Common/lib/vsts-task-lib/task.js
function getDelimitedInput(name, delim, required) {
    var inval = getInput(name, required);
    if (!inval) {
        return [];
    }
    return inval.split(delim);
}
function getDelimitedInput(name, delim, required) {
    var inval = getInput(name, required);
    if (!inval) {
        return [];
    }
    return inval.split(delim);
}
Split - do not use for splitting args!  Instead use arg() - it will split and handle this is for splitting a simple list of items like targets