@Override
  public void unpause() {
    isPaused = false;
    // TODO: unpause fetching
  }
stripeRgs[stripeIx'] => boolean array (could be a bitmask) of rg-s that need to be read.
Contains only stripes that are read, and only columns included. null => read all RGs.
llap-server/src/java/org/apache/hadoop/hive/llap/io/encoded/OrcEncodedDataReader.java