Resolves https://github.com/spring-projects/spring-integration/issues/3661 * Don't allow existing listener; remove unnecessary try/catch; add what's new. * Fix link in whats-new.adoc
Resolves https://github.com/spring-projects/spring-integration/issues/3661 * Don't allow existing listener; remove unnecessary try/catch; add what's new. * Fix link in whats-new.adoc