If you make up a module map for Objective C protocol buffers, the compiler will complain about missing a declaration for GPBUnknownFieldSet which is used in this file.
@@ -32,6 +32,7 @@
#import "GPBArray.h"
#import "GPBCodedOutputStream_PackagePrivate.h"
+#import "GPBUnknownFieldSet.h"
@implementation GPBUnknownField {
@protected