Spring - Load from file with UTF-8

I have problem with using Spring for loading UTF-8 file.

This is what is working for me :

I have properties file, saved as UTF-8 with this content

global.variable.try=This is product variable
cache.location.filename.regions=regions
hacky.carky=éíáščýéíšž hehe haha hoho +íšářá

In my controller, I access it in two ways

@Controller
@RequestMapping(value = "/aserver")
public class AServerController {

@Value("${hacky.carky}")
    private String hackyCarky;  

    @RequestMapping(value = "/hackycarky", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    @ResponseBody
    public Object hackycarky(ServletRequest servletRequest, ServletResponse response) throws MalformedURLException, IOException{
        return hackyCarky;
    }   

    @RequestMapping(value = "/regions", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    @ResponseBody
    public Object regions(ServletRequest servletRequest, ServletResponse response) throws MalformedURLException, IOException{
        String filePath = "c:\\prace\\eclipse workspace\\czechtraditions\\server\\src\\main\\resources\\server-general.properties";
        return new String(Files.readAllBytes(Paths.get(filePath)), StandardCharsets.UTF_8);     
    }   
}

If I access /aserver/hackycarky, it gives desired output :

éíáščýéíšž hehe haha hoho +íšářá

However if I access /aserver/regions, the output is as following :

global.variable.try=This is product variable
cache.location.filename.regions=regions
hacky.carky=���??���?? hehe haha hoho +�?�?�

PS : I do not need access properties file, this is just test-case, to be sure, that the file is in correct format - therefore working as expected with @Value("${hacky.carky}")

The response header is same in both cases, having this property

Content-Type:application/json;charset=UTF-8

I do have filter an filter-mapping for utf-8 set in web.xml :

<filter>
    <filter-name>encoding-filter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>encoding-filter</filter-name>
    <url-pattern>/rest/*</url-pattern>
</filter-mapping>

I do have utf-8 setting in my pom.xml for maven :

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

The example of full address is http://localhost:8080/czechtraditions-server/rest/aserver/regions