code: public long openChangeset(Map<String, String> tags)
  	{
  		return osm.makeAuthenticatedRequest("changeset/create", "PUT", 
  				createOsmChangesetTagsWriter(tags), new IdResponseReader());
  	}
docs: Open a new changeset with the given tags
  @param tags tags of this changeset. Usually it is comment and source.
  
  @throws OsmAuthorizationException if the application does not have permission to edit the
  map (Permission.MODIFY_MAP)