return;
            }
            boolean wasAcquired = this.treeAcquired;
            log.debug("Switching tree");
            if ( t != null ) {
                log.debug("Acquired tree on switch " + t);
                t.acquire();
                this.treeAcquired = true;
            }
            else {
                this.treeAcquired = false;
            }

            this.tree = t;