NdArray implementations don't throw IllegalRankException as documented if no coordinates provided

Instead, when no coordinates are provided, we return the scalar at (0, 0, ...). Is this an important idiom that we are preserving, or a questionable choice, or simply a bug?

Here's an example of an abstract method of FloatNdArray that is documented to throw IllegalRankException:

 /**
   * Returns the float value of the scalar found at the given coordinates.
   *
   * . . .
   *
   * @param coordinates coordinates of the scalar to resolve
   * @return value of that scalar
   * @throws IndexOutOfBoundsException if some coordinates are outside the limits of their respective dimension
   * @throws IllegalRankException if number of coordinates is not sufficient to access a scalar element
   */
  float getFloat(long... coordinates);

Here's the implementation in FloatDenseNdArray:

  @Override
  public float getFloat(long... indices) {
    return buffer.getFloat(positionOf(indices, true));
  }

But if indices.length == 0, then positionOf does not throw the claimed IllegalRankException:

  long positionOf(long[] coords, boolean isValue) {
    if (coords == null || coords.length == 0) {
      return 0;
    }
    Validator.coordinates(dimensions, coords, isValue);
    return dimensions.positionOf(coords);
  }

从文档化的 FloatNdArray.getFloat 合约开始，将其与 FloatDenseNdArray.getFloat 和 positionOf 进行比较，尤其是零坐标分支。确定返回位置 0 处的标量是有意为之，还是违反了文档化的异常行为；当行为与其文档一致，并且在项目提供相关覆盖的情况下已添加或更新相关覆盖时，即视为完成。