Java 14 pattern matching instance of not woking

Hi, 

I create a simple maven  project 

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>tmp</artifactId>
    <version>1.0-SNAPSHOT</version>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <release>14</release>
                    <!--                    <source>${java.version}</source>-->
                    <!--                    <target>${java.version}</target>-->
                    <failOnError>true</failOnError>
                    <compilerArgs>--enable-preview</compilerArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

The other preview features works as expected but pattern mathching instance of will not compile