http://www.dropwizard.io/2.0.18/dropwizard-bom/dropwizard-dependencies/dropwizard-parent/dropwizard-jersey: Dropwizard is a Java framework for developing ops-friendly, high-performance, RESTful web applications.
  • Coda Hale
  • Nick Telford
  • Graham O'Regan
  • Ryan Kennedy
  • Camille Fournier
  • Carlo Barbara
  • Matt Veitas
  • Ryan Tenney
  • Jochen Schalanda
  • Glenn McAllister
  • Nick Babcock
  • Justin Plock
  • Artem Prigoda 
package io.dropwizard.jersey.sessions;

import javax.annotation.Nullable;
import javax.inject.Inject;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

public final class FlashFactory {
    private final HttpServletRequest request;

    @Inject
    public FlashFactory(HttpServletRequest request) {
        this.request = request;
    }

    @SuppressWarnings("rawtypes")
    @Nullable
    public Flash<?> provide(boolean doNotCreate) {
        if (request == null) {
            return null;
        }

        final HttpSession session = request.getSession(!doNotCreate);
        if (session != null) {
            return new Flash(session);
        }

        return null;
    }
}