[ObjC] Improve handing of the WKT ObjC Category additions.
Include a comment in the generated header about there being helpers
in GPBWellKnowTypes.h
Generate some extra code for the WKTs that have categories to help
ensure the categories get linked so developers don't have to use
-ObjC in some cases.
PiperOrigin-RevId: 589179237
diff --git a/objectivec/GPBDuration.pbobjc.h b/objectivec/GPBDuration.pbobjc.h
index 9e67afc..c5e27e4 100644
--- a/objectivec/GPBDuration.pbobjc.h
+++ b/objectivec/GPBDuration.pbobjc.h
@@ -123,6 +123,9 @@
**/
@property(nonatomic, readwrite) int32_t nanos;
+// NOTE: There are some Objective-C specific methods/properties in
+// GPBWellKnownTypes.h that will likey be useful.
+
@end
NS_ASSUME_NONNULL_END
