prevent empty required

Author: krasnoukhov

lib/rspec_api_documentation/writers/open_api_writer.rb

@@ -270,8 +270,10 @@ def inject_body_parameter(schema, parameter)
 
         return unless scope.properties
 
-        scope.required ||= []
-        scope.required << parameter[:name].to_s if parameter[:required]
+        if parameter[:required]
+          scope.required ||= []
+          scope.required << parameter[:name].to_s
+        end
 
         scope.properties[parameter[:name].to_s] ||= get_schema(parameter[:value])
         scope.properties[parameter[:name].to_s].description = parameter[:description] if parameter[:description]