public GeogigTransaction(Context locator, UUID transactionId) {
Preconditions.checkArgument(!(locator instanceof GeogigTransaction));
this.injector = locator;
this.transactionId = transactionId;
transactionIndex = new TransactionStagingArea(new Index(this), transactionId);
transactionWorkTree = new WorkingTree(this);
transactionRefDatabase = new TransactionRefDatabase(locator.refDatabase(), transactionId);
}