PS D:\CS\test> javac src/Test.java
PS D:\CS\test> 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">
  <property name="haltOnException" value="true"/>
  <module name="TreeWalker">
    <module name="UnnecessaryParentheses">
    </module>
  </module>
</module>
PS D:\CS\test> cat src/Test.java

public class Test {
    void test(int x) {
        boolean a = (x == 3); // violation
        boolean b = (!(x == 3)); // violation

        boolean c = (x == 3) ? (x == 3) : (!(x == 3));  // expected 3 violations
    }

}
PS D:\CS\test> java  -jar checkstyle-10.17.0-all.jar -c config.xml  src/Test.java
Starting audit...
[ERROR] D:\CS\test\src\Test.java:4:21: Unnecessary parentheses around assignment right-hand side. [UnnecessaryParentheses]
[ERROR] D:\CS\test\src\Test.java:5:21: Unnecessary parentheses around assignment right-hand side. [UnnecessaryParentheses]
Audit done.
Checkstyle ends with 2 errors.