Fix copyright notices
diff --git a/src/ProtocolBuffers.Test/DescriptorsTest.cs b/src/ProtocolBuffers.Test/DescriptorsTest.cs
index 913a919..30758c0 100644
--- a/src/ProtocolBuffers.Test/DescriptorsTest.cs
+++ b/src/ProtocolBuffers.Test/DescriptorsTest.cs
@@ -29,12 +29,10 @@
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-using System;
-using System.Collections.Generic;
using System.Text;
-using NUnit.Framework;
using Google.ProtocolBuffers.Descriptors;
using Google.ProtocolBuffers.TestProtos;
+using NUnit.Framework;
namespace Google.ProtocolBuffers {
/// <summary>