docs: public Object lookup(Identity oid)
      {
          CacheEntry entry = null;
          SoftReference ref = (SoftReference) objectTable.get(oid);
          if (ref != null)
          {
              entry = (CacheEntry) ref.get();
              if (entry == null || entry.lifetime < System.currentTimeMillis())
              {
                  objectTable.remove(oid);    // Soft-referenced Object reclaimed by GC
                  // timeout, so set null
                  entry = null;
              }
          }
          return entry != null ? entry.object : null;
      }