Tab completion broken on JDK 25 after upgading jline to 3.30.9

[czpilar]

Tab completion no longer works after upgrading the jline dependency to the current 3.30.9. The regression depends on the JDK version: on JDK 21 completion works again as of 3.30.8, but on JDK 25 it has been broken since 3.30.7 and is still broken in 3.30.9.

I tried downgrading jline to find the first bad version. Results:

jline version	JDK 21	JDK 25
3.30.6	works	works
3.30.7	broken	broken
3.30.8	works	broken
3.30.9	works	broken

The jline upgrade in spring-shell happened in commit 9a829a7c (3.30.6 to 3.30.9).

Steps to reproduce:

1. Use spring-shell main (jline pinned to 3.30.9).
2. Run on JDK 25:

   ./mvnw -pl :spring-shell-sample-spring-boot spring-boot:run
   

3. At the shell:> prompt, press <TAB> - no candidates are shown.

Expected: the list of available commands (or option names after a command) is shown, as it is on JDK 21 with the same jline version, or on JDK 25 with <jline.version>3.30.6</jline.version>.

[czpilar]

Update / workaround confirmed:

Running with --enable-native-access=ALL-UNNAMED makes completion work again on JDK 25 with jline 3.30.9:

./mvnw -pl :spring-shell-sample-spring-boot spring-boot:run -Dspring-boot.run.jvmArguments="--enable-native-access=ALL-UNNAMED"

So the regression on JDK 25 is caused by JEP 472 restricted-method enforcement — jline's native/FFM calls are blocked by default on JDK 25 unless native access is explicitly enabled, and the failure cascades into completion not working. This is also documented in the https://jline.org/docs/troubleshooting/.

It would be helpful to document this in the spring-shell reference docs (e.g. a "Running on JDK 24+" section) so users don't have to bisect jline versions to find this. A note like:

When running a spring-shell application on JDK 24 or newer, pass --enable-native-access=ALL-UNNAMED (classpath apps) or --enable-native-access=<module> (modular apps) to the JVM. Without it, JLine's native terminal calls are restricted by JEP 472 and features such as tab completion silently fail. See the https://jline.org/docs/troubleshooting/ for details.

[fmbenhassine]

Thank you for reporting this issue and for bissecting jLine versions. I don't know if jLine follows semantic versioning, but there shouldn't be any breaking change in patch releases. Anyway, I tried to reproduce this issue but I am not able to do so with the latest main (d91b1b9, same as v4.0.2) with jLine 3.30.9:

> java -version
openjdk version "25.0.1" 2025-10-21
OpenJDK Runtime Environment (build 25.0.1+8-27)
OpenJDK 64-Bit Server VM (build 25.0.1+8-27, mixed mode, sharing)

> ./mvnw -pl :spring-shell-sample-spring-boot spring-boot:run
WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::load has been called by org.fusesource.jansi.internal.JansiLoader in an unnamed module (file:/Users/mbh/.m2/wrapper/dists/apache-maven-3.8.9-bin/2kle4jou91mnvqf35ph06hhh3a/apache-maven-3.8.9/lib/jansi-2.4.0.jar)
WARNING: Use --enable-native-access=ALL-UNNAMED to avoid a warning for callers in this module
WARNING: Restricted methods will be blocked in a future release unless native access is enabled

WARNING: A terminally deprecated method in sun.misc.Unsafe has been called
WARNING: sun.misc.Unsafe::objectFieldOffset has been called by com.google.common.util.concurrent.AbstractFuture$UnsafeAtomicHelper (file:/Users/mbh/.m2/wrapper/dists/apache-maven-3.8.9-bin/2kle4jou91mnvqf35ph06hhh3a/apache-maven-3.8.9/lib/guava-25.1-android.jar)
WARNING: Please consider reporting this to the maintainers of class com.google.common.util.concurrent.AbstractFuture$UnsafeAtomicHelper
WARNING: sun.misc.Unsafe::objectFieldOffset will be removed in a future release
[INFO] Scanning for projects...
[INFO]
[INFO] -----< org.springframework.shell:spring-shell-sample-spring-boot >------
[INFO] Building Spring Shell Samples - Hello World with Spring Boot 4.0.3-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] >>> spring-boot-maven-plugin:4.0.6:run (default-cli) > test-compile @ spring-shell-sample-spring-boot >>>
[INFO]
[INFO] --- spring-javaformat-maven-plugin:0.0.47:validate (default) @ spring-shell-sample-spring-boot ---
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ spring-shell-sample-spring-boot ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 2 resources
[INFO]
[INFO] --- flatten-maven-plugin:1.7.3:flatten (flatten) @ spring-shell-sample-spring-boot ---
[INFO] Generating flattened POM of project org.springframework.shell:spring-shell-sample-spring-boot:jar:4.0.3-SNAPSHOT...
[INFO]
[INFO] --- maven-compiler-plugin:3.14.1:compile (default-compile) @ spring-shell-sample-spring-boot ---
[INFO] Nothing to compile - all classes are up to date.
[INFO]
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ spring-shell-sample-spring-boot ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/mbh/projects/spring-shell/spring-shell-samples/spring-shell-sample-spring-boot/src/test/resources
[INFO]
[INFO] --- maven-compiler-plugin:3.14.1:testCompile (default-testCompile) @ spring-shell-sample-spring-boot ---
[INFO] No sources to compile
[INFO]
[INFO] <<< spring-boot-maven-plugin:4.0.6:run (default-cli) < test-compile @ spring-shell-sample-spring-boot <<<
[INFO]
[INFO]
[INFO] --- spring-boot-maven-plugin:4.0.6:run (default-cli) @ spring-shell-sample-spring-boot ---
[INFO] Attaching agents: []

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/

 :: Spring Boot ::                (v4.0.6)

14:37:10.446 [main] INFO  o.s.s.s.h.b.SpringShellApplication - Starting SpringShellApplication using Java 25.0.1 with PID 30955 (/Users/mbh/projects/spring-shell/spring-shell-samples/spring-shell-sample-spring-boot/target/classes started by mbh in /Users/mbh/projects/spring-shell/spring-shell-samples/spring-shell-sample-spring-boot)
14:37:10.447 [main] INFO  o.s.s.s.h.b.SpringShellApplication - No active profile set, falling back to 1 default profile: "default"
14:37:10.636 [main] INFO  o.h.validator.internal.util.Version - HV000001: Hibernate Validator 9.0.1.Final
14:37:10.793 [main] INFO  o.s.s.s.h.b.SpringShellApplication - Started SpringShellApplication in 0.454 seconds (process running for 0.625)
shell:>hel
Built-In Commands
help: Show help about available commands
Greetings
hello: Say hello to a given name

While I see the warning as mentioned in jLine's docs, I am still able to complete commands with Tab. However, I am on MacOS and I use iTerm:

And

This seems like a jLine issue specific to Windows. I will try on a Linux box as well.

[czpilar]

@fmbenhassine It might be a Windows-only issue. I tried the same setup with multiple versions mentioned above, and what helped was adding the --enable-native-access=ALL-UNNAMED directive.

It is definitely unfortunate to see this JLine behavior change between fix versions, but in the end, it is solvable.

[fmbenhassine]

I tested on Linux as well (Spring Shell 4.0.2, jLine 3.30.9), and the issue does not happen neither (completion works as expected):

So this seems to be specific to Windows only. But even on Windows, Spring Shell users should not have to add that flag to make things work.

It is definitely unfortunate to see this JLine behavior change between fix versions

Indeed, and what bothers me the most is the following note from jLine docs:

Notes

- The warning is harmless — JLine's native code operates correctly regardless. It is purely informational.
[...]

This does not seem to be accurate since it impacts completion. I will try to isolate the issue with jLine (no Spring Shell involved), in which case I will report it to jLine (if someone manages to do that in the meantime, I would be grateful).