code: function buildResourceMap(resourceDefinitions, start) {
      var map = {};
      if(resourceDefinitions) {
        for(var i = 0, len = resourceDefinitions.length; i < len; i++) {
          addResourceToMap(map, resourceDefinitions[i], start);
        }
      }
  
      return map;
    }
docs: Creates a map from the resource definitions that contains the schedule
  information for each of the resources (specifically when the resource
  will be next available and how to calculate future availability).