only classes and overridable class members can be declared 'open'

Author: George Nyakundi

boat-scaffold/src/main/templates/boat-swift5/api.mustache

@@ -22,7 +22,7 @@ extension {{moduleName}}Client {
 {{/swiftUseApiNamespace}}
 
 /// {{classname}} protocol defines a blueprint of methods, properties, and other requirements for {{classname}} functionality. 
-{{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}open{{/nonPublicApi}} protocol {{classname}}Protocol {
+{{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}public{{/nonPublicApi}} protocol {{classname}}Protocol {
 {{#operation}}
 
     /**