code: @SuppressWarnings("unchecked")
      public QueryBuilder and(final DBObject... ands) {
          List l = (List) _query.get(QueryOperators.AND);
          if (l == null) {
              l = new ArrayList();
              _query.put(QueryOperators.AND, l);
          }
          Collections.addAll(l, ands);
          return this;
      }
docs: Equivalent to an $and operand
  
  @param ands the list of conditions to and together
  @return {@code this}