feat(build): Add Checkstyle plugin and an IllegalImport rule

build-logic/src/main/kotlin/polaris-java.gradle.kts

@@ -30,18 +30,31 @@ plugins {
   `java-library`
   `java-test-fixtures`
   `jvm-test-suite`
+  checkstyle
   id("polaris-spotless")
   id("jacoco-report-aggregation")
   id("net.ltgt.errorprone")
 }
 
 apply<PublishingHelperPlugin>()
 
-if (project.extra.has("duplicated-project-sources")) {
-  // skip the style check for duplicated projects
-  tasks.withType<Checkstyle>().configureEach { enabled = false }
+checkstyle {
+  val checkstyleVersion =
+    versionCatalogs
+      .named("libs")
+      .findVersion("checkstyle")
+      .orElseThrow { GradleException("checkstyle version not found in libs.versions.toml") }
+      .requiredVersion
+  toolVersion = checkstyleVersion
+  configFile = rootProject.file("codestyle/checkstyle.xml")
+  isIgnoreFailures = false
+  maxErrors = 0
+  maxWarnings = 0
 }
 
+// Ensure Checkstyle runs after jandex to avoid task dependency issues
+tasks.withType<Checkstyle>().configureEach { tasks.findByName("jandex")?.let { mustRunAfter(it) } }
+
 tasks.withType(JavaCompile::class.java).configureEach {
   options.compilerArgs.addAll(listOf("-Xlint:unchecked", "-Xlint:deprecation"))
   options.errorprone.disableAllWarnings = true

build-logic/src/main/kotlin/polaris-spotless.gradle.kts

@@ -18,8 +18,6 @@
  */
 
 import com.diffplug.spotless.FormatterFunc
-import gradle.kotlin.dsl.accessors._fa00c0b20184971a79f32516372275b9.java
-import gradle.kotlin.dsl.accessors._fa00c0b20184971a79f32516372275b9.spotless
 import java.io.Serializable
 import org.gradle.api.GradleException
 

codestyle/checkstyle.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0"?>
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing,
+ software distributed under the License is distributed on an
+ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ KIND, either express or implied.  See the License for the
+ specific language governing permissions and limitations
+ under the License.
+-->
+<!DOCTYPE module PUBLIC
+  "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+  "https://checkstyle.org/dtds/configuration_1_3.dtd">
+
+<module name="Checker">
+  <property name="charset" value="UTF-8"/>
+  <property name="severity" value="warning"/>
+  <property name="fileExtensions" value="java, properties, xml"/>
+
+  <!-- Excludes all 'module-info.java' files              -->
+  <!-- See https://checkstyle.org/config_filefilters.html -->
+  <module name="BeforeExecutionExclusionFileFilter">
+    <property name="fileNamePattern" value="module\-info\.java$"/>
+  </module>
+
+  <!-- https://checkstyle.org/config_filters.html#SuppressionFilter -->
+  <module name="SuppressionFilter">
+    <property name="file" value="${org.checkstyle.google.suppressionfilter.config}"
+      default="checkstyle-suppressions.xml" />
+    <property name="optional" value="true"/>
+  </module>
+
+  <module name="TreeWalker">
+    <!-- Checks for imports                            -->
+    <!-- See http://checkstyle.org/config_imports.html -->
+    <module name="IllegalImport">
+      <property name="illegalPkgs" value=".*\.shaded\..*, .*\.relocated\..*"/>
+      <property name="regexp" value="true"/>
+    </module>
+
+  </module>
+</module>

gradle/libs.versions.toml

@@ -18,6 +18,7 @@
 #
 
 [versions]
+checkstyle = "10.25.0"
 hadoop = "3.4.1"
 iceberg = "1.9.0" # Ensure to update the iceberg version in regtests to keep regtests up-to-date
 quarkus = "3.21.4"

plugins/spark/v3.5/spark/build.gradle.kts

@@ -112,44 +112,6 @@ dependencies {
   }
 }
 
-// TODO: replace the check using gradlew checkstyle plugin
-tasks.register("checkNoDisallowedImports") {
-  doLast {
-    // List of disallowed imports. Right now, we disallow usage of shaded or
-    // relocated libraries in the iceberg spark runtime jar.
-    val disallowedImports =
-      listOf("import org.apache.iceberg.shaded.", "org.apache.iceberg.relocated.")
-
-    // Directory to scan for Java files
-    val sourceDirs = listOf(file("src/main/java"), file("src/test/java"))
-
-    val violations = mutableListOf<String>()
-    // Scan Java files in each directory
-    sourceDirs.forEach { sourceDir ->
-      fileTree(sourceDir)
-        .matching {
-          include("**/*.java") // Only include Java files
-        }
-        .forEach { file ->
-          val content = file.readText()
-          disallowedImports.forEach { importStatement ->
-            if (content.contains(importStatement)) {
-              violations.add(
-                "Disallowed import found in ${file.relativeTo(projectDir)}: $importStatement"
-              )
-            }
-          }
-        }
-    }
-
-    if (violations.isNotEmpty()) {
-      throw GradleException("Disallowed imports found! $violations")
-    }
-  }
-}
-
-tasks.named("check") { dependsOn("checkNoDisallowedImports") }
-
 tasks.register<ShadowJar>("createPolarisSparkJar") {
   archiveClassifier = "bundle"
   isZip64 = true

quarkus/test-commons/build.gradle.kts

@@ -24,9 +24,11 @@ plugins {
 }
 
 configurations.all {
-  exclude(group = "org.antlr", module = "antlr4-runtime")
-  exclude(group = "org.scala-lang", module = "scala-library")
-  exclude(group = "org.scala-lang", module = "scala-reflect")
+  if (name != "checkstyle") {
+    exclude(group = "org.antlr", module = "antlr4-runtime")
+    exclude(group = "org.scala-lang", module = "scala-library")
+    exclude(group = "org.scala-lang", module = "scala-reflect")
+  }
 }
 
 dependencies {