docs: protected void computeCardinality() {
      this.cardinality = 0;
      if (BufferUtil.isBackedBySimpleArray(bitmap)) {
        long[] b = this.bitmap.array();
        for (int k = 0; k < b.length; k++) {
          this.cardinality += Long.bitCount(b[k]);
        }
      } else {
        int m = this.bitmap.limit();
        for (int k = 0; k < m; k++) {
          this.cardinality += Long.bitCount(this.bitmap.get(k));
        }
      }
    }