[pom] Add comment on jdk8 requirement for hsqldb 2.4.0

Author: hazendaz

pom.xml

@@ -210,7 +210,7 @@
     <dependency>
       <groupId>org.hsqldb</groupId>
       <artifactId>hsqldb</artifactId>
-      <version>2.3.4</version>
+      <version>2.3.4</version> <!-- Version 2.4.0 required jdk8 -->
       <scope>test</scope>
     </dependency>
     <dependency>