Update gradle.md

Author: janbodnar

gradle.md

@@ -3,6 +3,15 @@
 
 ## Executable JAR
 
+*With plain JAR plugin:*
+
+This is the default Gradle task for creating a JAR archive. It packages your  
+compiled class files (*.class) and resources from your project into a single JAR  
+file.  
+
+It does not include any dependencies in the JAR. Your application needs the  
+libraries it depends on to be installed separately on the target system.  
+
 ```gradle
 plugins {
     id 'java'
@@ -17,18 +26,67 @@ repositories {
 }
 
 application {
-    // Define the main class for the application.
-    mainClass = 'com.example.Main'
+    mainClass = 'com.zetcode.Main'
 }
 
 jar {
-  manifest {
-    attributes(
-      'Main-Class': 'com.example.Main'
-    )
-  }
-  from {
-    configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
-  }
+    duplicatesStrategy(DuplicatesStrategy.EXCLUDE)
+    manifest {
+        attributes(
+                'Main-Class': 'com.zetcode.Main'
+        )
+    }
+    from {
+        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
+    }
 }
 ```
+
+*With shadow JAR plugin:*  
+
+It creates a fat JAR or shadow JAR, which is a single JAR containing your  
+application code and all its transitive dependencies.  
+
+It makes deployment easier as you only need to distribute the single JAR file  
+containing everything your application needs. The JAR file will be larger due to  
+the inclusion of all dependencies.  
+
+
+```gradle
+plugins {
+    id 'java'
+    id 'application'
+    id 'io.github.goooler.shadow' version '8.1.8'
+}
+
+group = 'com.zetcode'
+version = '1.0-SNAPSHOT'
+
+repositories {
+    mavenCentral()
+}
+
+application {
+    mainClass = 'com.zetcode.Main'
+}
+
+dependencies {
+    implementation 'org.eclipse.collections:eclipse-collections:11.1.0'
+}
+
+jar {
+//    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+    duplicatesStrategy(DuplicatesStrategy.EXCLUDE)
+    exclude 'META-INF/*.RSA', 'META-INF/*.SF', 'META-INF/*.DSA'
+    manifest {
+        attributes(
+                'Main-Class': 'com.zetcode.Main'
+        )
+    }
+    from {
+        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
+    }
+}
+```
+
+