Finalized solution

 Here comes my (til now) final solution for scanning folders recursive and setting the create date for files found. Let me know if you see any problems :) And let me know in the comments if you'd like more.

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// Pass in JSON string or JS Object, it is returned as beautified JSON

//

function prettyJSON(jsonString) {

// If object is passed, convert it to a jsonString

if (typeof(jsonString) == "object") {

jsonString = toJson(jsonString)

}

// Import Java classes

var ObjectMapper = new Packages.com.fasterxml.jackson.databind.ObjectMapper;

// Now get an Object Mapper

    var objectMapper = new ObjectMapper();

    // Need to use ObjectMapper to create our JS Object here

    var jsonObject = objectMapper.readValue(jsonString, java.lang.Object);

    // Return the beautified code

    return objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(jsonObject);

}

var supportedExtentions = {

dv: true,

jpg: true,

avi: true, 

mpg: true,

mp4: true,

psd: true

}

function supportedType(fileName) {

var parts = system.splitString(fileName, ".");

if (parts.length <= 1) return true;

for (var ext in supportedExtentions) {

if (ext.equalsIgnoreCase(parts[parts.length-1].trim())) return true

}

return false

}

// Recursive function to spin through a folder (java.io.File or String) 

// and sub-folders and return a JS fileListObject. Each property of the object 

// is a sub-object with its property name being the path to the file, 

// ensuring uniqueness for property names. Each object has the following three properties:

//

//  "\\FilesToFix\\Clip 08.dv": {

//    "folder": "FilesToFix",

//    "name": "Clip 08.dv",

//    "date": "20021224 18:34:18.953+0100"

//  }

//

// JS Objects are handy carriers of objects, and can be any primitive 

// Ecmascript 3 type or a Java object, like an Entry, Attribute or java.util.HashMap.

//

function getFiles(folder, fileListObjectArg) {

// Initialize the object if not passed in

var fileListObject = fileListObjectArg || {};

// If the folder name pass passed in, convert it to a File object

if (typeof(folder == "string")) { 

var useFolder = new java.io.File(folder);

if (!useFolder) throw "Cannot open folder: " + folder;

folder = useFolder

}

// Get the folder name and list of files in it

var folderName = folder.getName();

var fileList = folder.listFiles();

// If any files found, run through the returned list of java.io.File objects

if (fileList) {

for (file in fileList) {

var fileName = file.getName();

// If it's a directory then call this function recursively, 

// passing in the current state of the fileListObject

if (file.isDirectory()) {

getFiles(file, fileListObject);

} else

if (supportedType(fileName)) {

var dateString = system.formatDate(new java.util.Date(), "YYYYMMDD HH:mm:ss.SSSZ");

fileListObject[file.getPath()] = {

date: dateString,

name: fileName,

folder: folderName

}

}

}

}

return fileListObject

}

function setCreateDate(fromPath) {

var regexForDates = /(\d{4})\D(\d{2})\D(\d{2})(?:_(\d{4})\D(\d{2})\D(\d{2}))?/;

var regexForSingleDate = /(\d{4})\D(\d{2})$/;

var filesObj = getFiles(fromPath, {});

var Runtime = java.lang.Runtime;

// First count the files in each folder, saving this total

var fileCount = {};

var filesAL = new java.util.ArrayList();

for (var fullPath in filesObj) {

var file = filesObj[fullPath];

fileCount[file.folder] = (fileCount[file.folder] || 0) + 1

filesAL.add(fullPath);

}

var sortedFullPaths = filesAL.toArray();

java.util.Arrays.sort(sortedFullPaths);

var filesHandled = {};

var match = null;

var lastFolder = "";

for (var fullPath in sortedFullPaths) {

var file = filesObj[fullPath];

match = file.folder.match(regexForDates);

if (!match) { // Try just looking for yyyy-MM

match = file.folder.match(regexForSingleDate)

}

if (!match) continue; // No date found

// Increment the file count for this folder

filesHandled[file.folder] = (filesHandled[file.folder] || 0) + 1;

// Parse out the dates matched in the folder name

var dates = makeDates(match)

/*

task.logmsg(LJ(file.folder,25) + " -> " 

+ LJ(system.formatDate(dates.first, "YYYY.MM.dd"), 10) + "  _  " 

+ system.formatDate(dates.second, "YYYY.MM.dd"));

*/

var dateCreated = calcDate(dates.first, dates.second, filesHandled[file.folder], fileCount[file.folder], file.folder);

// Construct PowerShell command

var psCommand = 'powershell.exe -Command "Set-ItemProperty -Path \'' + fullPath + '\' -Name CreationTime -Value \'' + dateCreated + '\'"';

// Execute the command using Java Runtime

var process = Runtime.getRuntime().exec(psCommand);

// Wait for the process to complete

process.waitFor();

// Log the output

if (file.folder != lastFolder) {

task.logmsg("");

lastFolder = file.folder

}

task.logmsg("    >" + psCommand);

//task.logmsg("DateCreated set for: " + LJ(fullPath, 80) + " to " + dateCreated);

}

}

// Calculate the date between the first and second passed, based on total/index*100 (pct)

function calcDate(firstDate, secondDate, index, total, folder) {

    var pct = index / total;

    var diff = secondDate.getTime() - firstDate.getTime();

    var retDate;

    if (index == 1) {

        retDate = firstDate; // First index = firstDate

    } else if (index == total) {

        retDate = secondDate; // Last index = secondDate

    } else {

        retDate = new java.util.Date(firstDate.getTime() + (diff * pct));

    }

/*

if (index == 1) task.logmsg("");

task.logmsg("-----------------> " + LJ(folder, 25) + "   "

+ LJ(index + "/" + total, 10) + LJ(Math.round(pct*100) + "%", 8)

+ "   --   " + LJ(firstDate.toString(), 8) + " <<  " 

+ LJ(retDate.toString(), 8)

+ " << " + LJ(secondDate.toString(), 8));

*/

    return retDate;

}

// Left justified text

function LJ(txt, len) {

txt = txt || "";

len = len || txt.length;

return (txt + "                                                                                                       ").substring(0, len)

}

// Converts string to an int

function toInt(str, defVal) {

var intVal;

try {

intVal = system.toInt(str)

} catch (notAnIntException) {

intVal = defVal

}

return intVal

}

// The mc argument is the array resulting from doing a regex .match against the folder name

// It expects 1 date string in the format YYYY.MM.DD, possibly a second 

// In the first case, match will have a length of 4. If two are found, the length will be 7

function makeDate(mc, whichOne) {

var offset = (whichOne == 1) ? 0 : 3;

var year = toInt(mc[1 + offset] || mc[1]);

var month = toInt(mc[2 + offset] || mc[2] || 1);

var day = toInt(mc[3 + offset] || mc[3] || 15)

var cal = java.util.Calendar.getInstance();

cal.set(year, month - 1, day);

return cal.getTime()

}

// Returns an object with first and second date properties

// The mc argument is the array resulting from doing a regex .match against the folder name

function makeDates(mc) {

return {

first: makeDate(mc, 1),

second: makeDate(mc, 2)

}

}