code: public Object lookup(Identity oid)
      {
          Object obj = null;
          SoftReference ref = (SoftReference) objectTable.get(oid);
          if (ref != null)
          {
              obj = ref.get();
              if (obj == null)
              {
                  objectTable.remove(oid);    // Soft-referenced Object reclaimed by GC
              }
          }
          return obj;
      }
docs: Lookup object with Identity oid in objectTable.
  Returns null if no matching id is found