MetaClass error REST service

I have developed a REST service to return a list of strings and it is giving me this error:

ERROR c.h.r.s.ServicesControllerManager - MetaClass for service collection parameter type class java.lang.String not found

Service in

 List<String> fechasInventarios(String tienda, String tipo);

Service in rest-services.xml

  <service name="inventarios_FechasInventariosService">
        <method name="fechasInventarios">
            <param type="java.lang.String" name="tienda"/>
            <param type="java.lang.String" name="tipo"/>

What is wrong?

Thanks in advance!

this is a bug. It occurs when your method returns an empty list. The issue: