/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.ops4j.pax.web.samples.whiteboard.ds;

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.ServiceScope;
import org.osgi.service.http.whiteboard.HttpWhiteboardConstants;

@Component(
        service = {Servlet.class, WhiteboardErrorPage.class}, // WhiteboardErrorPage only for testing
        scope = ServiceScope.PROTOTYPE,
        property = {
                HttpWhiteboardConstants.HTTP_WHITEBOARD_SERVLET_ERROR_PAGE + "=java.io.IOException," +
                HttpWhiteboardConstants.HTTP_WHITEBOARD_SERVLET_ERROR_PAGE + "=404"
        }
)
public class WhiteboardErrorPage extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/plain");
        resp.getWriter().println("Error Servlet, we do have a 404");
    }
}

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.ops4j.pax.web.samples.whiteboard.ds;

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.ServiceScope;
import org.osgi.service.http.whiteboard.HttpWhiteboardConstants;

@Component(
        service = {Servlet.class, WhiteboardErrorPage.class}, // WhiteboardErrorPage only for testing
        scope = ServiceScope.PROTOTYPE,
        property = {
                HttpWhiteboardConstants.HTTP_WHITEBOARD_SERVLET_ERROR_PAGE + "=java.io.IOException",
                HttpWhiteboardConstants.HTTP_WHITEBOARD_SERVLET_ERROR_PAGE + "=404"
        }
)
public class WhiteboardErrorPage extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/plain");
        resp.getWriter().println("Error Servlet, we do have a 404");
    }
}

Fix whiteboard/ds/WhiteboardErrorPage (sorry, my mistake)