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