feat: suppress Maven transfer progress via MAVEN_ARGS by default

Set MAVEN_ARGS to include -ntp (--no-transfer-progress) so Maven invocations
in the job produce cleaner CI logs without download/transfer progress noise.
Add a new optional 'show-download-progress' input (default false); set it to
true to keep the progress output.

The change preserves any existing MAVEN_ARGS value (the flag is appended,
not overwritten) and is idempotent (it won't add the flag twice if -ntp or
--no-transfer-progress is already present). Applies on all platforms; honored
by Maven 3.9.0+ and the Maven Wrapper, and is a no-op for non-Maven builds.

- action.yml: add show-download-progress input
- src/constants.ts: add input + MAVEN_ARGS constants
- src/maven-args.ts: new configureMavenArgs()
- src/setup-java.ts: invoke configureMavenArgs() during setup
- __tests__/maven-args.test.ts: unit tests
- docs/advanced-usage.md: document the behavior and input
- dist: rebuild bundled action

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

docs/advanced-usage.md

@@ -18,6 +18,7 @@
 - [Testing against different Java distributions](#Testing-against-different-Java-distributions)
 - [Testing against different platforms](#Testing-against-different-platforms)
 - [Publishing using Apache Maven](#Publishing-using-Apache-Maven)
+- [Maven transfer progress (download logs)](#Maven-transfer-progress-download-logs)
 - [Publishing using Gradle](#Publishing-using-Gradle)
 - [Hosted Tool Cache](#Hosted-Tool-Cache)
 - [Modifying Maven Toolchains](#Modifying-Maven-Toolchains)
@@ -490,6 +491,36 @@ jobs:
         GITHUB_TOKEN: ${{ github.token }}
 ```
 
+## Maven transfer progress (download logs)
+
+By default, Maven prints a line for every artifact it downloads, which can add hundreds of noisy lines to CI logs. To keep logs clean, `setup-java` sets the [`MAVEN_ARGS`](https://maven.apache.org/configure.html#maven_args-environment-variable) environment variable to include `-ntp` (`--no-transfer-progress`) so that subsequent Maven invocations in the job suppress this transfer progress output.
+
+This is enabled by default. Any existing `MAVEN_ARGS` value is preserved (the flag is appended, not overwritten), and the flag is not added twice if you already set it yourself.
+
+If you want to keep the download/transfer progress in your logs, set `show-download-progress: true`:
+
+```yaml
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v6
+    - uses: actions/setup-java@v5
+      with:
+        distribution: '<distribution>'
+        java-version: '21'
+        show-download-progress: true # keep Maven download/transfer progress in the logs
+
+    - name: Build with Maven
+      run: mvn -B package --file pom.xml
+```
+
+***NOTES***:
+- `MAVEN_ARGS` is honored by Maven 3.9.0+ and the Maven Wrapper (`mvnw`). Older Maven versions ignore it, so on those you can pass `--no-transfer-progress` on the command line instead.
+- This setting only affects Maven. It has no effect on Gradle, sbt, or other build tools.
+- `-ntp` only controls transfer/progress output; it does not change whether Maven runs in batch mode. Use `-B`/`--batch-mode` (or `<interactiveMode>false</interactiveMode>` in `settings.xml`) if you also want non-interactive runs.
+
 ## Publishing using Gradle
 ```yaml
 jobs: