RSRP-54545: error CS0415: The 'IndexerName' attribute is valid only on an indexer that is not an explicit interface member declaration

using System;
using System.Runtime.CompilerServices;

interface I
{
    int this[int x] { get; set; }
}

class A : I
{
    [IndexerName("Foo")]
    int I.this[int x] // error CS0415: The 'IndexerName' attribute is valid only on an indexer that is not an explicit interface member declaration
    {
        get { throw new NotImplementedException(); }
        set { throw new NotImplementedException(); }
    }
}