See https://github.com/spring-projects/spring-integration/pull/2837
Give priority to accepting new connections over reading data from
existing connections.
Add a flag to allow users to revert to the previous behavior of
giving reads priority.
**cherry-pick to 5.1.x**
# Conflicts:
# spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioServerConnectionFactory.java
# src/reference/asciidoc/whats-new.adoc
# TcpNioConnectionTests.java
6f3fd0961f