code: function PrimitiveGroup(properties) {
              this.nodes = [];
              this.ways = [];
              this.relations = [];
              this.changesets = [];
              if (properties)
                  for (var keys = Object.keys(properties), i = 0; i < keys.length; ++i)
                      if (properties[keys[i]] != null)
                          this[keys[i]] = properties[keys[i]];
          }
docs: Properties of a PrimitiveGroup.
  @memberof OSMPBF
  @interface IPrimitiveGroup
  @property {Array.<OSMPBF.INode>|null} [nodes] PrimitiveGroup nodes
  @property {OSMPBF.IDenseNodes|null} [dense] PrimitiveGroup dense
  @property {Array.<OSMPBF.IWay>|null} [ways] PrimitiveGroup ways
  @property {Array.<OSMPBF.IRelation>|null} [relations] PrimitiveGroup relations
  @property {Array.<OSMPBF.IChangeSet>|null} [changesets] PrimitiveGroup changesets
   
  Constructs a new PrimitiveGroup.
  @memberof OSMPBF
  @classdesc Represents a PrimitiveGroup.
  @implements IPrimitiveGroup
  @constructor
  @param {OSMPBF.IPrimitiveGroup=} [properties] Properties to set