code: private boolean isContainedIn(BitSet sourceBitSet, BitSet targetBitSet) {
          boolean result = false;
  
          if (sourceBitSet.isEmpty()) {
              return true;
          }
  
          BitSet setA = (BitSet) sourceBitSet.clone();
          setA.and(targetBitSet);
  
          if (setA.equals(sourceBitSet)) {
              result = true;
          }
  
          return result;
      }
docs: Test if set sourceBitSet is contained in  set targetBitSet.
  @param  sourceBitSet  a bitSet
  @param  targetBitSet  a bitSet
  @return    true if  sourceBitSet is contained in  targetBitSet