Merge branch 'anotherPassAt37th' of https://github.com/chester89/fluent-nhibernate into chester89-anotherPassAt37th

Author: jagregory

src/FluentNHibernate.Testing/FluentInterfaceTests/ElementPartTests.cs

@@ -33,5 +33,18 @@ public void CanSetFormula()
             ElementMapping elementMapping = ((IElementMappingProvider)part).GetElementMapping();
             elementMapping.Formula.ShouldEqual("formula");
         }
+
+        [Test]
+      	public void CanDeclareColumnNullable()
+        {
+      	    var part = new ElementPart(typeof(MappedObject));
+            part.Column("nullabilityCheck");
+      	    part.Nullable();
+
+            ElementMapping elementMapping = ((IElementMappingProvider)part).GetElementMapping();
+            var columnMappings = elementMapping.Columns.ToList();
+            columnMappings.First().Nullable.ShouldEqual(true);
+      	
+        }
     }
 }

src/FluentNHibernate/Mapping/ElementPart.cs

@@ -66,6 +66,15 @@ public ElementPart Formula(string formula)
             return this;
         }
 
+        /// <summary>
+      	/// Specify the nullability of the column
+        /// </summary>
+        public ElementPart Nullable()
+        {
+            columnAttributes.Set("NotNull", Layer.UserSupplied, false);
+            return this;
+        }
+
         ElementMapping IElementMappingProvider.GetElementMapping()
         {
             var mapping = new ElementMapping(attributes.Clone());

src/FluentNHibernate/MappingModel/ColumnMapping.cs

@@ -47,6 +47,11 @@ public bool NotNull
             get { return attributes.GetOrDefault<bool>("NotNull"); }
         }
 
+        public bool Nullable
+        {
+             get { return !NotNull; }
+        }
+
         public bool Unique
         {
             get { return attributes.GetOrDefault<bool>("Unique"); }