Hi! Reading the instructions from https://help.liferay.com/hc/en-us/articles/360018161391-Making-Your-Applications-Configurable it sounds like it is sufficient to define a single interface and get a fully configuration UI in the system settings. 
I defined the following interface:

package com.example.config;

import com.liferay.portal.configuration.metatype.annotations.ExtendedObjectClassDefinition;
import aQute.bnd.annotation.metatype.Meta;

@ExtendedObjectClassDefinition(scope = ExtendedObjectClassDefinition.Scope.SYSTEM )
@Meta.OCD(id = "com.example.config.JasperReportsConfiguration")
public interface JasperReportsConfiguration {    
    @Meta.AD(deflt = "/var/liferay/jasperTemplates", required = true)
    public String jasperReportTemplateLocation();
}

However when I navigate to System Settings >> Other there is no entry for this specific configuration. I'am using Liferay 7.0 EE.I am looking forward to any help. Thanks. Jürgen