Update jdiff.stable.api from 2.9.1 to 2.9.2.

hadoop-project-dist/pom.xml

@@ -144,7 +144,7 @@
         <activeByDefault>false</activeByDefault>
       </activation>
       <properties>
-        <jdiff.stable.api>2.9.1</jdiff.stable.api>
+        <jdiff.stable.api>2.9.2</jdiff.stable.api>
         <jdiff.stability>-unstable</jdiff.stability>
         <!-- Commented out for HADOOP-11776 -->
         <!-- Uncomment param name="${jdiff.compatibility}" in javadoc doclet if compatibility is not empty -->