Skip adding metadata if value is null

appveyor.yml

@@ -14,4 +14,4 @@ artifacts:
 - path: '**\*.nupkg'
   name: NuGet Packages
 on_failure:
-- ps: Get-ChildItem .\*.log -Recursive | % { Push-AppveyorArtifact $_.FullName -FileName $_.Name }
+- ps: Get-ChildItem .\*log -Recurse | % { Push-AppveyorArtifact $_.FullName -FileName $_.Name }

src/MSBuildProjectCreator.UnitTests/ItemTests.cs

@@ -131,6 +131,29 @@ public void ItemIncludeNotAddedIfNull()
                     StringCompareShould.IgnoreLineEndings);
         }
 
+        [Fact]
+        public void MetadataNotAddedIfNull()
+        {
+            ProjectCreator.Create(projectFileOptions: NewProjectFileOptions.None)
+                .ItemInclude(
+                    itemType: "DB5003A476FA461EB0452DDDCCE7F802",
+                    include: "303F33834A6843EDB44DB8D3186E97E0",
+                    metadata: new Dictionary<string, string>
+                    {
+                        { "CDBA5A760C9C45CFB2E9532D4B4AE2B7", "D6A68EA723C848E19D2E17C09F7F2532" },
+                        { "FDD9C6C5582B404188CD8C938DB2CDD9", null }
+                    })
+                .Xml.ShouldBe(
+                    @"<Project>
+  <ItemGroup>
+    <DB5003A476FA461EB0452DDDCCE7F802 Include=""303F33834A6843EDB44DB8D3186E97E0"">
+      <CDBA5A760C9C45CFB2E9532D4B4AE2B7>D6A68EA723C848E19D2E17C09F7F2532</CDBA5A760C9C45CFB2E9532D4B4AE2B7>
+    </DB5003A476FA461EB0452DDDCCE7F802>
+  </ItemGroup>
+</Project>",
+                    StringCompareShould.IgnoreLineEndings);
+        }
+
         [Fact]
         public void NoneItem()
         {

src/MSBuildProjectCreator/ProjectCreator.Items.cs

@@ -5,6 +5,7 @@
 using Microsoft.Build.Construction;
 using Microsoft.Build.Evaluation;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace Microsoft.Build.Utilities.ProjectCreation
 {
@@ -291,7 +292,7 @@ private ProjectCreator Item(
 
             if (metadata != null)
             {
-                foreach (KeyValuePair<string, string> metadatum in metadata)
+                foreach (KeyValuePair<string, string> metadatum in metadata.Where(i => i.Value != null))
                 {
                     item.AddMetadata(metadatum.Key, metadatum.Value);
                 }