无法检索显式接口实现的成员

我正在使用Roslyn来分析C#代码,并且在使用明确实现的接口时遇到了一个问题.给定一个实现接口的类型,我无法按名称检索显式实现的成员.例如:

var tree = CSharpSyntaxTree.ParseText(@"
using System;

namespace ConsoleApplication1
{
    class MyClass : IDisposable
    {
        void IDisposable.Dispose()
        {
        }
        public void Dispose()
        {
        }
    }
}");

var Mscorlib = new MetadataFileReference(typeof(object).Assembly.Location); 
var compilation = CSharpCompilation.Create("MyCompilation",
    syntaxTrees: new[] { tree }, references: new[] { Mscorlib });
var model = compilation.GetSemanticModel(tree);

var myType = compilation.GetTypeByMetadataName("ConsoleApplication1.MyClass");
var dispose = myType.GetMembers("Dispose").SingleOrDefault();
//explicitDispose is null.
var explicitDispose = myType.GetMembers("IDisposable.Dispose").SingleOrDefault();

仅当类型存在于命名空间内时才会出现这种情况,以下代码可以正常工作.

var tree = CSharpSyntaxTree.ParseText(@"
class MyClass : IDisposable
{
    void IDisposable.Dispose()
    {
    }
    public void Dispose()
    {
    }
}");
var Mscorlib = new MetadataFileReference(typeof(object).Assembly.Location); 
var compilation = CSharpCompilation.Create("MyCompilation",
    syntaxTrees: new[] { tree }, references: new[] { Mscorlib });
var model = compilation.GetSemanticModel(tree);

var myType = compilation.GetTypeByMetadataName("MyClass");
var dispose = myType.GetMembers("Dispose").SingleOrDefault();
//explicitDispose is not null.
var explicitDispose = myType.GetMembers("IDisposable.Dispose").SingleOrDefault();

有谁知道为什么会这样？有没有更好的方法来使用显式实现的接口？