Inherit parts to child parts

Author: twsouthwick

src/DocumentFormat.OpenXml/Framework/PartConstraintCollection.cs

@@ -25,7 +25,7 @@ public static PartConstraintCollection Create<T>(Func<Type, OpenXmlElementData>
         {
             var collection = new PartConstraintCollection();
 
-            foreach (var constraint in type.GetTypeInfo().GetCustomAttributes(inherit: false).OfType<T>())
+            foreach (var constraint in type.GetTypeInfo().GetCustomAttributes(inherit: true).OfType<T>())
             {
                 collection.Add(new PartConstraintRule(dataFactory(constraint.ConstraintType).Info, constraint.MinOccursIsNonZero, constraint.MaxOccursGreatThanOne));
             }

test/DocumentFormat.OpenXml.Packaging.Tests/PartConstraintCollectionTypes.cs

@@ -3,6 +3,7 @@
 
 using DocumentFormat.OpenXml.Framework;
 using System;
+using System.IO;
 using Xunit;
 
 #pragma warning disable IDE0028 // Simplify collection initialization
@@ -78,6 +79,25 @@ public void ContainsRelationshipTest()
             Assert.False(collection.ContainsRelationship("b"));
         }
 
+        [Fact]
+        public void PartsAreInherited()
+        {
+            using (var m = new MemoryStream())
+            using (var doc = SpreadsheetDocument.Create(m, SpreadsheetDocumentType.Workbook, true))
+            {
+                var wb = doc.AddWorkbookPart();
+
+                // Adding new worksheet part using custom worksheetpart derived class
+                var ws = wb.AddNewPart<PsWorksheetPart>();
+
+                Assert.NotNull(ws.AddNewPart<SpreadsheetPrinterSettingsPart>());
+            }
+        }
+
+        private sealed class PsWorksheetPart : WorksheetPart
+        {
+        }
+
         [RelationshipType(Relationship)]
         private class ConstraintTest1
         {