anchor.diff:                  value();
       } else if (ex instanceof MissingConfKeyException) {
           response.setHeader(
  -                SyncopeClientErrorHandler.EXCEPTION_TYPE_HEADER,
  -                SyncopeClientExceptionType.NotFound.getHeaderValue());
  +                SyncopeClientErrorHandler.EXCEPTION_TYPE_HEADER, SyncopeClientExceptionType.NotFound.getHeaderValue());
           response.setHeader(
                   SyncopeClientExceptionType.NotFound.getElementHeaderName(),
                   ((MissingConfKeyException) ex).getConfKey());
  
positive.code:                 SyncopeClientErrorHandler.EXCEPTION_TYPE_HEADER,
                  SyncopeClientExceptionType.InvalidExternalResource.getHeaderValue());
          response.setHeader(
                  SyncopeClientExceptionType.InvalidExternalResource.
                  getElementHeaderName(),
                  ex.getCause() == null ? ex.getMessage() : ex.getCause().
                  getMessage());
  
  
negative.code: <%@page isErrorPage="true" session="false" contentType="application/json" pageEncoding="UTF-8"%>
  <%@page import="org.springframework.orm.jpa.JpaSystemException"%>
  <%@page import="org.syncope.types.EntityViolationType"%>
  <%@page import="java.util.Set"%>
  <%@page import="java.util.Map"%>
  