Fixed encoding issue in ErrorController

package it.inaf.oats.vospace.exception;

import java.nio.charset.StandardCharsets;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

    public void errorText(HttpServletRequest request, HttpServletResponse response) throws Exception {

        Map<String, Object> errors = super.getErrorAttributes(request, true);

        response.setContentType("text/plain;charset=UTF-8");

        response.getOutputStream().print((String) errors.get("message"));

        response.setCharacterEncoding("UTF-8");

        String errorMessage = (String) errors.get("message");

        if (errorMessage != null) {

            response.getOutputStream().write(errorMessage.getBytes(StandardCharsets.UTF_8));

        }

    }

    @Override