/var/tmp $ javac Test2.java

/var/tmp $ cat config.xml
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
        "https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name="Checker">
    <module name="TreeWalker">
        <module name="SummaryJavadocCheck"/>
    </module>
</module>

/var/tmp $ cat Test2.java
// unexpected violation below
/**
 * This is the actual summary.
 * {@summary This is wrong usage}
 */
public class Test2 {
}

// expected violation below
/**
 * This is summary
 */
class foo {
}

/var/tmp $ RUN_LOCALE="-Duser.language=en -Duser.country=US"
/var/tmp $ java $RUN_LOCALE -jar checkstyle-9.2.1-all.jar -c config.xml Test2.java
Starting audit...
[ERROR] /home/vyom/IdeaProjects/ConfigCheckstyle/src/TestP/Test2.java:2: Summary of Javadoc is missing an ending period. [SummaryJavadoc]
[ERROR] /home/vyom/IdeaProjects/ConfigCheckstyle/src/TestP/Test2.java:10: First sentence of Javadoc is missing an ending period. [SummaryJavadoc]
Audit done.
Checkstyle ends with 2 errors.