INT-3030 Add Error Channel to RMI Inbound Gateway

INT-3030 Polishing; Docs, Tests

Add test cases for error channel support.

Dynamically discover available RMI port.

Add What's New and `<important/>` to reference.

src/reference/docbook/rmi.xml

@@ -32,6 +32,13 @@
     <property name="requestChannel" value="requests"/>
 </bean>]]></programlisting>
     </para>
+    <important>
+    If you use an <code>errorChannel</code> on an inbound gateway, it would be normal for the error flow to return a result
+    (or throw an exception). This is because it is likely that there is a corresponding outbound gateway waiting for a
+    response of some kind. Consuming a message on the error flow, and not replying, will result in no reply at the inbound
+    gateway. Exceptions (on the main flow when there is no errorChannel, or on the error flow) will be propagated to the
+    corresponding inbound gateway.
+    </important>
   </section>
 
   <section id="rmi-namespace">
@@ -47,7 +54,7 @@
     registry-host="localhost"/>
 
 <int-rmi:inbound-gateway id="gatewayWithPort" request-channel="testChannel"
-    registry-port="1234"/>
+    registry-port="1234" error-channel="rmiErrorChannel"/>
 
 <int-rmi:inbound-gateway id="gatewayWithExecutorRef" request-channel="testChannel"
     remote-invocation-executor="invocationExecutor"/>]]></programlisting>

src/reference/docbook/whats-new.xml

@@ -201,6 +201,13 @@
 				in addition to several other container attributes that were already available.
 			</para>
 		</section>
+		<section id="3.0-rmi-ec">
+			<title>RMI Inbound Gateway</title>
+			<para>
+				The RMI Inbound Gateway now supports an <code>error-channel</code> attribute. See
+				<xref linkend="rmi-inbound"/>.
+			</para>
+		</section>
 		<section id="3.0-stored-proc-sql-return-type">
 			<title>SqlReturnType support for Stored Procedure components</title>
 			<para>