Incompatible with JDK 21

[lalib]

What happened?

Failed with using Spotless Maven plugin and palantir rule:

[INFO] --- spotless:2.39.0:apply (default-cli) @ X ---
[ERROR] Step 'palantir-java-format' found problem in 'X.java':
253:44: error: expected token: '_'; generated  instead
com.palantir.javaformat.java.FormatterException: 253:44: error: expected token: '_'; generated  instead
    at com.palantir.javaformat.java.Formatter.getFormatReplacements (Formatter.java:302)
    at com.palantir.javaformat.java.Formatter.formatSource (Formatter.java:277)
    at com.palantir.javaformat.java.Formatter.formatSource (Formatter.java:245)
    at com.diffplug.spotless.glue.pjf.PalantirJavaFormatFormatterFunc.apply (PalantirJavaFormatFormatterFunc.java:43)
    at com.diffplug.spotless.FormatterFunc.apply (FormatterFunc.java:32)
    at com.diffplug.spotless.FormatterStepImpl$Standard.format (FormatterStepImpl.java:82)
    at com.diffplug.spotless.FormatterStep$Strict.format (FormatterStep.java:103)
    at com.diffplug.spotless.Formatter.compute (Formatter.java:246)
    at com.diffplug.spotless.PaddedCell.calculateDirtyState (PaddedCell.java:203)
    at com.diffplug.spotless.PaddedCell.calculateDirtyState (PaddedCell.java:190)
    at com.diffplug.spotless.maven.SpotlessApplyMojo.process (SpotlessApplyMojo.java:48)
    at com.diffplug.spotless.maven.AbstractSpotlessMojo.execute (AbstractSpotlessMojo.java:229)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:126)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:342)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:330)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:213)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:175)
    at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:76)
    at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:163)
    at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:160)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:73)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:53)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:260)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:172)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:100)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:821)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:270)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:103)
    at java.lang.reflect.Method.invoke (Method.java:580)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)

[booniepepper]

Also saw a failure (although a slightly different one) with Spotless and Gradle here: https://github.com/openfga/java-sdk/actions/runs/6510767947/job/17685150920?pr=27

[koppor]

This issue should be refined: When did you encounter this issue? I tried the plugin on Java 21 in a JavaFX project (at koppor/jabref#663) - and it worked.

[ollehallin]

This code fails to format with palantir-java-format 2.39.0:

final var currentOffsets = new HashMap<Integer, Long>();

currentOffsets.computeIfAbsent(partition, _ -> new AtomicLong()).set(consumerRecord.offset());

It generates

com.palantir.javaformat.java.FormatterException: 156:60: error: expected token: '_'; generated instead -> [Help 1]

[koppor]

For the interested readers: Using _ is from JEP-443. Good explanation at https://howtodoinjava.com/java/unnamed-patterns-and-variables/