docs: public synchronized void addProjection( String externalNodeKey,
                                              String projectedNodeKey,
                                              String alias,
                                              SessionCache systemSession) {
          Projection projection = new Projection(externalNodeKey, projectedNodeKey, alias);
          storeProjection(projection, systemSession);
          Snapshot current = this.snapshot.get();
          Snapshot updated = current.withProjection(projection);
          this.snapshot.compareAndSet(current, updated);
      }