Issue with Interface Properties and Default Implementations in C#

Question

I'm encountering a problem with interface properties in C#. The predefined property DefinedProperty is not visible in the context of the class that implements the interface. Here is a code example:

interface IBase
{
    int Integer { get; set; }
    string DefinedProperty => Integer.ToString();
}

class Class : IBase
{
    public int Integer { get; set; }

    public void Foo()
    {
        Console.WriteLine(DefinedProperty); // Compile time error here
    }
}

I'm hoping someone can provide a clear explanation if there is one.