internal/testprotos: make TestAllExtensions recursive

Tweak the test message to allow creating messages with extensions that
contain extensions that contain extensions, etc.

Change-Id: I41844ae699c88ab96bf0d30db3a3fbaf09616161
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/216761
Reviewed-by: Joe Tsai <joetsai@google.com>
diff --git a/internal/impl/extension_test.go b/internal/impl/extension_test.go
index a8e2b68..4bf0258 100644
--- a/internal/impl/extension_test.go
+++ b/internal/impl/extension_test.go
@@ -63,7 +63,7 @@
 		},
 		{
 			xt:    testpb.E_OptionalNestedMessageExtension,
-			value: &testpb.TestAllTypes_NestedMessage{},
+			value: &testpb.TestAllExtensions_NestedMessage{},
 		},
 		{
 			xt:    testpb.E_OptionalNestedEnumExtension,
@@ -107,7 +107,7 @@
 		},
 		{
 			xt:    testpb.E_RepeatedNestedMessageExtension,
-			value: []*testpb.TestAllTypes_NestedMessage{{}},
+			value: []*testpb.TestAllExtensions_NestedMessage{{}},
 		},
 		{
 			xt:    testpb.E_RepeatedNestedEnumExtension,