Show how to publish the shadowed jar only (GradleUp#1150)

* Add publishShadowJarInsteadOfJarWithMavenPublishPlugin test

* Add an example in src/docs/publishing/README.md

src/docs/publishing/README.md

@@ -44,3 +44,45 @@ configuration of the POM file.
 This automatic configuration occurs _only_ when using the above methods for
 configuring publishing. If this behavior is not desirable, then publishing **must**
 be manually configured.
+
+
+## Publish the Shadowed JAR instead of the Original JAR
+
+You may want to publish the shadowed JAR instead of the original JAR. This can be done by trimming 
+the `archiveClassifier` of the shadowed JAR like the following:
+
+```groovy
+apply plugin: 'java'
+apply plugin: 'maven-publish'
+apply plugin: 'com.gradleup.shadow'
+
+group = 'shadow'
+version = '1.0'
+
+dependencies {
+  // This will be bundled in the shadowed JAR and not declared in the POM.
+  implementation 'some:a:1.0'
+  // This will be excluded from the shadowed JAR but declared as a runtime dependency in `META-INF/MANIFEST.MF`
+  // file's `Class-Path` entry, and also in the POM file.
+  shadow 'some:b:1.0'
+  // This will be excluded from the shadowed JAR and not declared in the POM or `META-INF/MANIFEST.MF`.
+  compileOnly 'some:c:1.0'
+}
+
+tasks.named('shadowJar', com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar) {
+  archiveClassifier = ''
+}
+
+publishing {
+  publications {
+    shadow(MavenPublication) {
+      from components.shadow
+    }
+  }
+  repositories {
+    maven {
+      url = "https://repo.myorg.com"
+    }
+  }
+}
+```

src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/PublishingTest.kt

@@ -11,6 +11,7 @@ import com.github.jengelman.gradle.plugins.shadow.util.Issue
 import com.github.jengelman.gradle.plugins.shadow.util.JarPath
 import com.github.jengelman.gradle.plugins.shadow.util.containsEntries
 import com.github.jengelman.gradle.plugins.shadow.util.doesNotContainEntries
+import com.github.jengelman.gradle.plugins.shadow.util.getMainAttr
 import com.squareup.moshi.JsonAdapter
 import com.squareup.moshi.Moshi
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
@@ -62,6 +63,37 @@ class PublishingTest : BasePluginTest() {
     assertPomCommon(repoPath("shadow/maven-all/1.0/maven-all-1.0.pom"))
   }
 
+  @Test
+  fun publishShadowJarInsteadOfJarWithMavenPublishPlugin() {
+    projectScriptPath.appendText(
+      publishConfiguration(
+        shadowBlock = """
+          archiveClassifier = ''
+        """.trimIndent(),
+        publicationsBlock = """
+          shadow(MavenPublication) {
+            from components.shadow
+          }
+        """.trimIndent(),
+      ),
+    )
+
+    publish()
+
+    assertThat(repoJarPath("shadow/maven/1.0/maven-1.0.jar")).useAll {
+      containsEntries(
+        "a.properties",
+        "a2.properties",
+      )
+      doesNotContainEntries(
+        "b.properties",
+      )
+      getMainAttr("Class-Path").isEqualTo("b-1.0.jar")
+    }
+    assertPomCommon(repoPath("shadow/maven/1.0/maven-1.0.pom"))
+    assertShadowVariantCommon(gmmAdapter.fromJson(repoPath("shadow/maven/1.0/maven-1.0.module")))
+  }
+
   @Issue(
     "https://github.com/GradleUp/shadow/issues/860",
     "https://github.com/GradleUp/shadow/issues/945",