Add a note to make it clear that the covariant IThenable support is a hack.
@@ -1593,6 +1593,8 @@ public abstract class JSType implements TypeI {
} else if (isIThenableSubtype(thatType)) {
// NOTE: special case IThenable subclass (Promise, etc). These classes are expected to be
// covariant.
+ // Also note that this ignores any additional template type arguments that might be defined
+ // on subtypes. If we expand this to other types, a more correct solution will be needed.
TemplateType key = thisType.registry.getThenableValueKey();
JSType thisElement = thisTypeParams.getResolvedTemplateType(key);
JSType thatElement = thatTypeParams.getResolvedTemplateType(key);
