private/model/api: Fix RESTXML support for XML Namespace

Fixes a bug with the SDK's generation of services using the REST XML
protocol not annotating shape references with the XML Namespace
attribute.

Fix aws#1334

private/model/api/shape.go

@@ -405,11 +405,12 @@ func (ref *ShapeRef) GoTags(toplevel bool, isRequired bool) string {
 		} else if ref.Shape.XMLNamespace.Prefix != "" {
 			tags = append(tags, ShapeTag{"xmlPrefix", ref.Shape.XMLNamespace.Prefix})
 		}
-		if ref.XMLNamespace.URI != "" {
-			tags = append(tags, ShapeTag{"xmlURI", ref.XMLNamespace.URI})
-		} else if ref.Shape.XMLNamespace.URI != "" {
-			tags = append(tags, ShapeTag{"xmlURI", ref.Shape.XMLNamespace.URI})
-		}
+	}
+
+	if ref.XMLNamespace.URI != "" {
+		tags = append(tags, ShapeTag{"xmlURI", ref.XMLNamespace.URI})
+	} else if ref.Shape.XMLNamespace.URI != "" {
+		tags = append(tags, ShapeTag{"xmlURI", ref.Shape.XMLNamespace.URI})
 	}
 
 	if ref.IdempotencyToken || ref.Shape.IdempotencyToken {

private/protocol/restxml/build_test.go

@@ -3586,7 +3586,7 @@ func (c *InputService19ProtocolTest) InputService19TestCaseOperation1WithContext
 type InputService19TestShapeGrant struct {
 	_ struct{} `locationName:"Grant" type:"structure"`
 
-	Grantee *InputService19TestShapeGrantee `type:"structure"`
+	Grantee *InputService19TestShapeGrantee `type:"structure" xmlURI:"http://www.w3.org/2001/XMLSchema-instance"`
 }
 
 // SetGrantee sets the Grantee field's value.