chore: run Lint Java once

.github/workflows/pr_build_linux.yml

@@ -48,10 +48,13 @@ jobs:
 
   # Fast syntactic-only scalafix check. Parses sources without compiling, so it
   # surfaces version-independent style issues (e.g. RedundantSyntax) in seconds,
-  # long before the lint-java matrix finishes its ~3.5 min build. It also scans
-  # the spark-4.1 / spark-4.2 sources that lint-java skips (those profiles can't
-  # run -Psemanticdb yet), so it is the only gate covering them. The full rule
-  # set, including the semantic rules, still runs in lint-java.
+  # long before lint-java finishes its ~3.5 min build. It is also the only gate
+  # covering the Spark profiles lint-java skips: 3.4, 3.5, 4.1, and 4.2. Spark
+  # 4.1 / 4.2 skip lint-java because -Psemanticdb can't run against their Scala
+  # versions (see the note on lint-java below); the 3.x profiles are skipped to
+  # keep the lint matrix to a single row pinned to the latest supported Spark.
+  # The full rule set, including the semantic rules, runs in lint-java against
+  # that single profile.
   scalafix-syntactic:
     name: Lint Scala (syntactic)
     runs-on: ubuntu-24.04
@@ -72,42 +75,28 @@ jobs:
             --exclude '**/target/**' \
             spark
 
+  # Semantic scalafix + prettier + working-tree check, pinned to a single
+  # Spark 4.0 / JDK 21 row. 4.0 is the latest Spark that can currently run
+  # -Psemanticdb: semanticdb-scalac for the Scala 2.13.17 / 2.13.18 patch
+  # versions used by spark-4.1 / spark-4.2 has not been published yet. JDK 21
+  # is the newest JDK in the supported test matrix. Cross-version syntactic
+  # coverage is provided by scalafix-syntactic above.
   lint-java:
     needs: lint
-    name: Lint Java (${{ matrix.profile.name }})
+    name: Lint Java (Spark 4.0, JDK 21)
     runs-on: ubuntu-24.04
     container:
       image: amd64/rust
       env:
-        JAVA_TOOL_OPTIONS: ${{ (matrix.profile.java_version == '17' || matrix.profile.java_version == '21') && '--add-exports=java.base/sun.nio.ch=ALL-UNNAMED --add-exports=java.base/sun.util.calendar=ALL-UNNAMED --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED' || '' }}
-    strategy:
-      matrix:
-        profile:
-          - name: "Spark 3.4, JDK 11, Scala 2.12"
-            java_version: "11"
-            maven_opts: "-Pspark-3.4 -Pscala-2.12"
-          - name: "Spark 3.5, JDK 17, Scala 2.12"
-            java_version: "17"
-            maven_opts: "-Pspark-3.5 -Pscala-2.12"
-          - name: "Spark 4.0, JDK 17"
-            java_version: "17"
-            maven_opts: "-Pspark-4.0"
-          - name: "Spark 4.0, JDK 21"
-            java_version: "21"
-            maven_opts: "-Pspark-4.0"
-          # Spark 4.1 and 4.2 are intentionally absent: the lint job invokes -Psemanticdb,
-          # but semanticdb-scalac for those Scala patch versions (2.13.17 / 2.13.18) is not
-          # yet published, so we cannot currently run scalafix against the spark-4.1 or
-          # spark-4.2 profiles.
-      fail-fast: false
+        JAVA_TOOL_OPTIONS: "--add-exports=java.base/sun.nio.ch=ALL-UNNAMED --add-exports=java.base/sun.util.calendar=ALL-UNNAMED --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED"
     steps:
       - uses: actions/checkout@v7
 
       - name: Setup Rust & Java toolchain
         uses: ./.github/actions/setup-builder
         with:
           rust-version: ${{ env.RUST_VERSION }}
-          jdk-version: ${{ matrix.profile.java_version }}
+          jdk-version: "21"
 
       - name: Cache Maven dependencies
         uses: actions/cache@v6
@@ -121,7 +110,7 @@ jobs:
 
       - name: Run scalafix check
         run: |
-          ./mvnw -B package -DskipTests scalafix:scalafix -Dscalafix.mode=CHECK -Psemanticdb ${{ matrix.profile.maven_opts }}
+          ./mvnw -B package -DskipTests scalafix:scalafix -Dscalafix.mode=CHECK -Psemanticdb -Pspark-4.0
 
       - name: Setup Node.js
         uses: actions/setup-node@v7