protected access modifier difference between Java and C#.

UnitTest1.cs

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTestProject1
{
    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {
            new B(new A()).Hoge().Is(10);
        }

        class A
        {
            protected int X = 10;
        }

        class B : A
        {
            private A _A;
            public B(A a)
            {
                _A = a;
            }
            public int Hoge()
            {
                //return _A.X; // Compile Error: CS1540 Cannot access protected member 'UnitTest1.A.X' via a qualifier of type 'UnitTest1.A'; the qualifier must be of type 'UnitTest1.B' (or derived from it)
                return base.X; // OK.
            }
        }
    }
}

UnitTest1.java

package UnitTestProject1;

import static org.junit.Assert.*;
import static org.hamcrest.CoreMatchers.*;
import org.junit.Test;

public class UnitTest1 {

	@Test
	public void test() {
		assertThat(new B(new A()).Hoge(), is(10));
	}

	class A {
		protected int X = 10;
	}

	class B extends A {
		private A _A;

		public B(A a) {
			_A = a;
		}

		public int Hoge() {
			return _A.X;
		}
	}
}