This filter starts an {@link HttpSession} at the start of the request to avoid JSF late session binding. Based on BalusC suggestions https://stackoverflow.com/questions/8072311/adding-hform-causes-java-lang-illegalstateexception-cannot-create-a-session.

SessionFilter.java

package com.bluelotussoftware.servlets.filter;

import java.io.IOException;
import java.text.MessageFormat;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/**
 * This filter starts an {@link HttpSession} at the start of the request to
 * avoid JSF late session binding. Based on BalusC suggestions
 * <a href="https://stackoverflow.com/questions/8072311/adding-hform-causes-java-lang-illegalstateexception-cannot-create-a-session">Cannot
 * create a session after the response has been committed</a>.
 *
 * @author John Yeary
 * @version 1.0
 */
public class SessionFilter implements Filter {

    private FilterConfig filterConfig;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        if (request instanceof HttpServletRequest) {
            HttpServletRequest httpServletRequest = (HttpServletRequest) request;
            HttpSession session = httpServletRequest.getSession(true);
            httpServletRequest.getServletContext().log(MessageFormat.format("Session created {0}", session.getId()));
            try {
                chain.doFilter(httpServletRequest, response);
            } catch (IOException | ServletException t) {
                httpServletRequest.getServletContext().log("An exception occurred during processing.", t);
            }
        }
    }

    @Override
    public void destroy() {
    }

}