code: public boolean removeAll(final Collection<?> c, final long occurrences) {
          checkOccurrences(occurrences);
  
          if (N.isNullOrEmpty(c) || occurrences == 0) {
              return false;
          }
  
          boolean result = false;
  
          for (Object e : c) {
              if (result == false) {
                  result = remove(e, occurrences);
              } else {
                  remove(e, occurrences);
              }
          }
  
          return result;
      }
docs: Remove the specified occurrences from the specified elements.
  The elements will be removed from this set if the occurrences equals to or less than 0 after the operation.
  
  @param c
  @param occurrences
  the occurrences to remove if the element is in the specified collection <code>c</code>.
  @return <tt>true</tt> if this set changed as a result of the call