JAR files building

Will build JAR for each 3 step separately when executing `gradlew build` or `gradlew jarStepX` where X is the step you want to export as JAR.
The generated JARs are located in `build/libs`.
To run a JAR, use `java -jar build/libs/stepX-1.0-SNAPSHOT.jar` where `X` is the step number

build.gradle.kts

@@ -2,6 +2,55 @@ plugins {
     id("java")
 }
 
+sourceSets {
+    create("common") {
+        java.srcDir("src/main/java/common")
+    }
+
+    // Step1-3 each depend on common
+    create("step1") {
+        java.srcDirs("src/main/java/common", "src/main/java/step1")
+    }
+    create("step2") {
+        java.srcDirs("src/main/java/common", "src/main/java/step2")
+    }
+    create("step3") {
+        java.srcDirs("src/main/java/common", "src/main/java/step3")
+    }
+}
+
+// === Create JAR tasks for each step ===
+tasks.register<Jar>("jarStep1") {
+    manifest {
+        attributes["Main-Class"] = "step1.Main"
+    }
+    archiveBaseName.set("step1")
+    from(sourceSets["step1"].output)
+    dependsOn("classes")
+}
+
+tasks.register<Jar>("jarStep2") {
+    manifest {
+        attributes["Main-Class"] = "step2.Main"
+    }
+    archiveBaseName.set("step2")
+    from(sourceSets["step2"].output)
+    dependsOn("classes")
+}
+
+tasks.register<Jar>("jarStep3") {
+    manifest {
+        attributes["Main-Class"] = "step3.Main"
+    }
+    archiveBaseName.set("step3")
+    from(sourceSets["step3"].output)
+    dependsOn("classes")
+}
+
+tasks.named("build") {
+    dependsOn("jarStep1", "jarStep2", "jarStep3")
+}
+
 group = "be.naaturel"
 version = "1.0-SNAPSHOT"