c# – 为什么ImmutableArray.Create复制一个现有的不可变数组？

var arr = ImmutableArray.Create('A','B','C','D');
 var bc ImmutableArray.Create(arr,1,2);

我希望我的两个ImmutableArrays可以在这里共享底层数组.但
当仔细检查这个时,我看到实现没有：

从2017年3月18日的15757a8开始

/// <summary>
    /// Initializes a new instance of the <see cref="ImmutableArray{T}"/> struct.
    /// </summary>
    /// <param name="items">The array to initialize the array with.
    /// The selected array segment may be copied into a new array.</param>
    /// <param name="start">The index of the first element in the source array to include in the resulting array.</param>
    /// <param name="length">The number of elements from the source array to include in the resulting array.</param>
    /// <remarks>
    /// This overload allows helper methods or custom builder classes to efficiently avoid paying a redundant
    /// tax for copying an array when the new array is a segment of an existing array.
    /// </remarks>
    [Pure]
    public static ImmutableArray<T> Create<T>(ImmutableArray<T> items,int start,int length)
    {
        Requires.Range(start >= 0 && start <= items.Length,nameof(start));
        Requires.Range(length >= 0 && start + length <= items.Length,nameof(length));

        if (length == 0)
        {
            return Create<T>();
        }

        if (start == 0 && length == items.Length)
        {
            return items;
        }

        var array = new T[length];
        Array.Copy(items.array,start,array,length);
        return new ImmutableArray<T>(array);
    }

为什么必须在这里制作基础项目的副本？
并不是这种方法的文档误导/错误？它说

This overload allows helper methods or custom builder classes to
efficiently avoid paying a redundant tax for copying an array when the
new array is a segment of an existing array.

但是,分段情况正好在它复制时,如果所需的切片为空或整个输入数组,它只会避免复制.

有没有另一种方法可以实现我想要的东西,而不是实现某种ImmutableArraySpan？