INT-3367: Add GemfireMetadataStore

JIRA: https://jira.spring.io/browse/INT-3367

INT-3367 Polishing

Rename test class; move to metadata package; doc polishing.

src/reference/docbook/gemfire.xml

@@ -200,4 +200,39 @@ Note the <emphasis>pool</emphasis> element is configured with the address of a c
 			</note>
 		</para>
 	</section>
+	<section id="gemfire-metadata-store">
+		<title>Gemfire Metadata Store</title>
+		<para>
+			As of <emphasis>Spring Integration 4.0</emphasis>, a new Gemfire-based
+			<interfacename>MetadataStore</interfacename>
+			(<xref linkend="metadata-store"/>) implementation is available. The <classname>GemfireMetadataStore</classname>
+			can be used to maintain metadata state
+			across application restarts. This new <interfacename>MetadataStore</interfacename>
+			implementation can be used with adapters such as:
+		</para>
+		<itemizedlist>
+			<listitem><xref linkend="twitter-inbound"/></listitem>
+			<listitem><xref linkend="feed-inbound-channel-adapter"/></listitem>
+			<listitem><xref linkend="file-reading"/></listitem>
+			<listitem><xref linkend="ftp-inbound"/></listitem>
+			<listitem><xref linkend="sftp-inbound"/></listitem>
+		</itemizedlist>
+		<para>
+			In order to instruct these adapters to use the new <classname>GemfireMetadataStore</classname>,
+			simply declare a Spring bean using the bean name <emphasis role="bold">metadataStore</emphasis>.
+			The <emphasis>Twitter Inbound Channel Adapter</emphasis> and the
+			<emphasis>Feed Inbound Channel Adapter</emphasis> will both automatically
+			pick up and use the declared <classname>GemfireMetadataStore</classname>.
+		</para>
+		<note>
+			<para>
+				The <classname>GemfireMetadataStore</classname> also implements
+				<interfacename>ConcurrentMetadataStore</interfacename>, allowing it to be reliably shared across
+				multiple application instances where only one instance will be allowed to store or modify a key's value.
+				These methods give various levels of concurrency guarantees based on the scope and data policy of the region.
+				They are implemented in the peer cache and client/server cache but are disallowed in peer Regions having
+				NORMAL or EMPTY data policies.
+			</para>
+		</note>
+	</section>
 </chapter>

src/reference/docbook/meta-data-store.xml

@@ -28,6 +28,7 @@
 	<itemizedlist>
 		<listitem>PropertiesPersistingMetadataStore</listitem>
 		<listitem><xref linkend="redis-metadata-store"/></listitem>
+		<listitem><xref linkend="gemfire-metadata-store"/></listitem>
 	</itemizedlist>
 	<para>
 		The <classname>PropertiesPersistingMetadataStore</classname> is backed by a properties file and a
@@ -49,7 +50,7 @@
 	<section id="idempotent-receiver">
 		<title>Idempotent Receiver</title>
 		<para>
-			The <emphasis>Metadata Store</emphasis> is useful for implementating the
+			The <emphasis>Metadata Store</emphasis> is useful for implementing the
 			EIP <ulink url="http://eaipatterns.com/IdempotentReceiver.html">Idempotent Receiver</ulink> pattern, when
 			there is need to <emphasis>filter</emphasis> an incoming Message if it has already been processed, and just discard
 			it or perform some other logic on discarding. The following configuration is an example of how to do this:

src/reference/docbook/whats-new.xml

@@ -182,6 +182,17 @@
 				For more information, see <xref linkend="twitter-sog"/>.
 			</para>
 		</section>
+		<section id="4.0-gemfire-metadata">
+			<title>Gemfire Metadata Store</title>
+			<para>
+				The <classname>GemfireMetadataStore</classname> is provided, allowing it to be used, for example,
+				in a <classname>AbstractPersistentAcceptOnceFileListFilter</classname>
+				implementation in a multiple application instance/server environment.
+				For more information, see <xref linkend="metadata-store"/>,
+				<xref linkend="file-reading"/>, <xref linkend="ftp-inbound"/> and
+				<xref linkend="sftp-inbound"/>.
+			</para>
+		</section>
 	</section>
 
 	<section id="4.0-general">