docs: public UpdateSketch buildLocal(final UpdateSketch shared) {
      if ((shared == null) || !(shared instanceof ConcurrentSharedThetaSketch)) {
        throw new SketchesStateException("The concurrent shared sketch must be built first.");
      }
      return new ConcurrentHeapThetaBuffer(bLocalLgNomLongs, bSeed,
          (ConcurrentSharedThetaSketch) shared, bPropagateOrderedCompact, bMaxNumLocalThreads);
    }