WIP: AVRO-4223 Gradle plugin for generating Java code

lang/java/.gitignore

@@ -20,3 +20,6 @@
 dependency-reduced-pom.xml
 mapred/userlogs/
 tools/userlogs/
+gradle-plugin/build
+gradle-plugin/.kotlin
+gradle-plugin/.gradle

lang/java/gradle-plugin/README.md

@@ -0,0 +1,77 @@
+# Avro Gradle plugin (in development)
+
+Gradle plugin that generates Java code from Avro schemas
+
+## Version
+`0.0.2`
+
+first beta
+
+`0.0.5`
+
+Possible breaking change: rename `CompileSchemaTask` to `CompileAvroSchemaTask`
+
+Add logical type factories
+
+Now released on Gradle plugin portal: https://plugins.gradle.org/plugin/eu.eventloopsoftware.avro-gradle-plugin
+
+`0.0.7`
+
+It is not needed to add `tasks.named("compileKotlin") { dependsOn(tasks.named("avroGenerateJavaClasses")) }` any more
+
+`0.0.8`
+
+Add `sourceZipFiles` property to add zip files with schemas in them
+pu
+
+## Usage
+
+### Add avro extension
+In `build.gradle.kts`:
+
+### Add plugin
+
+```kotlin
+plugins {
+    id("eu.eventloopsoftware.avro-gradle-plugin") version "0.0.8"
+}
+```
+### Add Avro dependency
+
+```kotlin
+implementation("org.apache.avro:avro:1.12.1")
+```
+
+### Configure Avro Gradle plugin
+
+```kotlin
+avro {
+    sourceDirectory = "src/main/avro"
+    // All properties are available in `GradlePluginExtension.kt`
+} 
+```
+
+### Generate Java classes
+
+`./gradlew avroGenerateJavaClasses`
+
+
+## Example project that uses the Apache Avro gradle-plugin
+https://codeberg.org/frevib/use-gradle-plugin-test
+
+## FAQ
+
+#### How can I benefit from Kotlin's null safety?
+Use `createNullSafeAnnotations = true` and Java getters will be annotated with 
+`@org.jetbrains.annotations.NotNull`/ `@org.jetbrains.annotations.Nullable`. This way
+Kotlin will recognize which value is nullable.
+
+#### I get my Avro schemas from a Maven dependency, how can I add JAR files that contain schemas?
+Use `sourceZipFiles = listOf("file_path")`, e.g.
+
+```kotlin
+avro {
+    sourceZipFiles = listOf("/home/user/.gradle/caches/modules-2/files-2.1/eu.eventloopsoftware.group-id/artifact-id/1.0.0/92ac3d0533de9dd79ac35373c892ebaa01763d4d/jar_with_schemas-1.0.0.jar")
+} 
+```
+

lang/java/gradle-plugin/build.gradle.kts

@@ -0,0 +1,60 @@
+/*
+ * 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
+ *
+ *     https://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.
+ */
+
+plugins {
+    kotlin("jvm") version "2.2.10"
+    `java-gradle-plugin`
+    id("com.gradle.plugin-publish") version "2.0.0"
+}
+
+group = "eu.eventloopsoftware"
+version = "0.0.9-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+    mavenLocal()
+}
+
+dependencies {
+    // TODO: for release use ${version}
+    implementation("org.apache.avro:avro-compiler:1.12.1")
+    implementation("org.jetbrains.kotlin:kotlin-gradle-plugin-api:2.3.0")
+    testImplementation(kotlin("test"))
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
+kotlin {
+    jvmToolchain(21)
+}
+
+
+gradlePlugin {
+    plugins {
+        website = "https://avro.apache.org/"
+        vcsUrl = "https://github.com/apache/avro.git"
+        register("gradlePlugin") {
+            id = "eu.eventloopsoftware.avro-gradle-plugin"
+            displayName = "Avro Gradle Plugin"
+            description = "Avro Gradle plugin for generating Java code"
+            tags = listOf("avro", "kotlin", "java", "apache")
+            implementationClass = "eu.eventloopsoftware.avro.gradle.plugin.AvroGradlePlugin"
+        }
+    }
+}

lang/java/gradle-plugin/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.2.1-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists