INT-2881: Add support for the firstRecord to retrieving JPA gateway

JIRA: https://jira.springsource.org/browse/INT-2881

src/reference/docbook/jpa.xml

@@ -1138,6 +1138,8 @@ public class Student {
     jpa-operations=""
     jpa-query=""
     max-number-of-results="" ]]><co id="outGateMaxNumOfResults"/><![CDATA[
+    first-result="" ]]><co id="outGateFirstResult"/><![CDATA[
+    first-result-expression="" ]]><co id="outGateFirstResultExpression"/><![CDATA[
     named-query=""
     native-query=""
     order=""
@@ -1168,6 +1170,20 @@ public class Student {
 						all the possible records are selected by given query.<emphasis>Optional</emphasis>.
 					</para>
 				</callout>
+				<callout arearefs="outGateFirstResult">
+					<para>
+						This non zero, non negative integer value tells the adapter the first record from which the
+						results are to be retrieved This attribute is mutually exclusive to <code>first-result-expression</code>.
+						This attribute is introduced since version 3.0. <emphasis>Optional</emphasis>.
+					</para>
+				</callout>
+				<callout arearefs="outGateFirstResultExpression">
+					<para>
+						This expression is evaluated against the message to find the position of first record in the
+						result set to be retrieved This attribute is mutually exclusive to <code>first-result</code>.
+						This attribute is introduced since version 3.0. <emphasis>Optional</emphasis>.
+					</para>
+				</callout>
 			</calloutlist>
 			<important>
 				<para>

src/reference/docbook/whats-new.xml

@@ -452,5 +452,14 @@
 				least 1.
 			</para>
 		</section>
+		<section id="3.0-jpa-first-result">
+			<title>JPA Adapters: first-result attribute</title>
+			<para>
+			    Retrieving gateways had no mechanism to specify the first record to be retrieved which
+			    is a common use case. The retrieving gateways now support specifying this parameter
+			    using a <code>first-result</code> and <code>first-result-expression</code> attributes
+			    to the gateway definition.<xref linkend="jpa-retrieving-outbound-gateway"/>
+			</para>
+		</section>
 	</section>
 </chapter>