To validate your HTL Scripts you can run the following command:
mvn org.apache.sling:htl-maven-plugin:validate
This assumes you’ve configured the ${project.build.sourceDirectory} setting.
The command can be simplified to
mvn htl:validate
if your Maven user settings file provides the following configuration
<pluginGroups>
<pluginGroup>org.apache.sling</pluginGroup>
</pluginGroups>
<project>
...
<build>
<pluginManagement>
<plugin>
<groupId>org.apache.sling</groupId>
<artifactId>htl-maven-plugin</artifactId>
<version>1.0.8/version>
<configuration>
<!-- put your configurations here -->
</configuration>
<executions>
<execution>
<goals>
<goal>validate</goal>
</goals>
</execution>
</executions>
</plugin>
</pluginManagement>
</build>
...
</project>