code: private void addMissingBlanks(final int index) {
          if (this.capacity <= index) {
              this.capacity = index * 2;
              final E[] newArr = (E[]) new Object[this.capacity];
              System.arraycopy(this.arr, 0, newArr, 0, this.size);
              this.arr = newArr;
          }
          if (this.blankElement != null) {
              Arrays.fill(this.arr, this.size, index, this.blankElement);
          }
          this.size = index + 1;
      }
docs: Postcondition: this.size == index + 1