Require JDK 17 for building

[gnodet]

Description

Bump the minimal JDK version required for building to java 17.

Motivation

This will streamline the build, allow upgrading to more recent plugins.
The minimal JDK requirement for runtime will be unchanged at JDK 8.

[garydgregory]

+1 here.

[tomaswolf]

This might require changing the CI builds. We still should test on Java 8. Might require maven toolchains.

Otherwise fine by me.

[gnodet]

This might require changing the CI builds. We still should test on Java 8. Might require maven toolchains.

I'm working on CI. I've set up a jdk8 profile which removes some plugins that require JDK 11. I don't think toolchains are required here.

[tomaswolf]

I'm working on CI. I've set up a jdk8 profile which removes some plugins that require JDK 11. I don't think toolchains are required here.

Then we're not really requiring Java 11 for building. So still no multi-release.

I would require 11 (or even 17) for compiling/building always; just run the tests on different JVMs (8, 11, 17). That's why I mentioned toolchains. I think there is a way to tell surefire to use a specific toolchain.

[gnodet]

I'm working on CI. I've set up a jdk8 profile which removes some plugins that require JDK 11. I don't think toolchains are required here.

Then we're not really requiring Java 11 for building. So still no multi-release.

I would require 11 (or even 17) for compiling/building always; just run the tests on different JVMs (8, 11, 17). That's why I mentioned toolchains. I think there is a way to tell surefire to use a specific toolchain.

The #537 PR now does that. I've bumped to JDK 21, but we can go down if we want.

[tomaswolf]

You can use JDK 21 in CI, but I would not require it as minimum for building.

Still looks more complicated that needed. I'm not at my development machine, so I cannot verify myself that this would work, but it seems to me the following patch would be a minimal change to build with Java 11 and test on JDK 8, 11, 17:

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 0eb87ee..7ab3828 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -29,15 +29,14 @@
     strategy:
       matrix:
         os: [ ubuntu-latest, windows-latest ]
-        java: [ '8' ]
     steps:
       - uses: actions/checkout@v4
 
-      - name: Set up JDK ${{ matrix.java }}
+      - name: Set up JDK 11
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: ${{ matrix.java }}
+          java-version: '11'
 
       - uses: actions/cache@v4
         with:
@@ -63,7 +62,10 @@
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: ${{ matrix.java }}
+          # Unsure whether this works if matrix.java == 11. If not, need two different setups with a conditional
+          java-version: |
+            ${{ matrix.java }}
+            '11'
 
       - uses: actions/cache@v4
         with:
@@ -74,7 +76,7 @@
 
       - name: Build and test with maven
         # Skip all static checks, they were already done in the compile jobs
-        run: mvn -B --errors --activate-profiles ci --no-transfer-progress package
+        run: mvn -B --errors --activate-profiles ci -Dtest.jdk.vendor=temurin -Dtest.jdk.version=${{ matrix.java }} --no-transfer-progress package
 
       - name: Archive test results and logs
         # if: success() || failure() to also get the test results on successful runs.
diff --git a/.github/workflows/master-build.yml b/.github/workflows/master-build.yml
index 7aa899e..1d5a991 100644
--- a/.github/workflows/master-build.yml
+++ b/.github/workflows/master-build.yml
@@ -47,7 +47,7 @@
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: '8'
+          java-version: '11'
           # Create a ~/.m2/settings.xml referencing these environment variable names
           server-id: 'apache.snapshots.https'
           server-username: NEXUS_USERNAME
diff --git a/pom.xml b/pom.xml
index fcbc28d..60ea820 100644
--- a/pom.xml
+++ b/pom.xml
@@ -138,9 +138,6 @@
     <profiles>
         <profile>
             <id>release</id>
-            <properties>
-                <required.java.version>[1.8,1.9)</required.java.version>
-            </properties>
         </profile>
 
         <profile>
@@ -149,6 +146,20 @@
                 <sshd.tests.timeout.factor>4.0</sshd.tests.timeout.factor>
                 <sshd.tests.rerun.count>4</sshd.tests.rerun.count>
             </properties>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <jdkToolchain>
+                               <version>${test.jdk.version}</version>
+                               <vendor>${test.jdk.vendor}</vendor>
+                            </jdkToolchain>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
         </profile>
 
         <profile>

This should use toolchains only in CI, so building locally doesn't require people to define toolchains manually. Adapting to build with Java 21 and running tests on 8,11,17,21 would be simple.