INT-3646: Add TCP Server Exception Events

JIRA: https://jira.spring.io/browse/INT-3646

Publish `TcpConnectionServerExceptionEvent`s when unexpected
exceptions occur on server sockets.

INT-3646: Polishing
Fix Reactor tests

src/reference/docbook/ip.xml

@@ -508,6 +508,11 @@
         point the exception occurred. Applications can use a normal <interfacename>ApplicationListener</interfacename>,
         or see <xref linkend="applicationevent-inbound"/>, to capture these events, allowing analysis of the problem.
     </para>
+    <para>
+        Starting with <emphasis>versions 4.0.7, 4.1.3</emphasis> <classname>TcpConnectionServerExceptionEvent</classname>s
+        are published whenever an unexpected exception occurs on a server socket (such as a <classname>BindException</classname>
+        when the server socket is in use). These events have a reference to the connection factory and the cause.
+    </para>
   </section>
   <section id="tcp-adapters">
     <title>TCP Adapters</title>

src/reference/docbook/whats-new.xml

@@ -39,5 +39,13 @@
 				<code>org.springframework.integration.scattergather</code>.
 			</para>
 		</section>
+		<section id="4.2-tcp-server-exceptions">
+			<title>Server Socket Exceptions</title>
+			<para>
+				<classname>TcpConnectionServerExceptionEvent</classname>s are now published whenever an
+				unexpected exception occurs on a TCP server socket (also added to 4.1.3, 4.0.7).
+				See <xref linkend="tcp-events"/> for more information.
+			</para>
+		</section>
 	</section>
 </chapter>