Use the experimental/preview Java language features,

Maven - modify pom.xml:

  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <configuration>
            <release>14</release>
            <compilerArgs>--enable-preview</compilerArgs>
          </configuration>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>

Gradle:

sourceCompatibility = 14
tasks.withType(JavaCompile) {
    options.compilerArgs += '--enable-preview'
}
tasks.withType(Test) {
    jvmArgs += "--enable-preview"
}