/*
convert `OrderArray: [ Order: [...] ]` structure to `Orders: []`.
@param parentObj: the obj *containing* the key to be restructured.
@param key: the key within the object to fix.
modifies byref.
@return new key.
function _flattenSillyArray(parentObj, key, requestContext) {
  //debug('_flattenSillyArray', key, parentObj[key]);

  var subKey = key.replace(/Array$/, '');   // e.g. 'Order' from 'OrderArray'
  var newKey = subKey + 's';                // e.g. 'Orders'

  // `compact` avoids creating an array of `[undefined]`,
  // from input `['']` when xml "array" element was empty.
  parentObj[newKey] = _.compact(parentObj[key][0][subKey]);
  delete parentObj[key];

  // might have already been flattened...
  if (!_.isArray(parentObj[newKey])) parentObj[newKey] = [ parentObj[newKey] ];

  parentObj[newKey] = parentObj[newKey].map(function(subObj) {
    return exports.flatten(subObj, -1, requestContext);
  });

  return newKey;
}