Publish an additional fat jar with Gradle

build.gradle

plugins {
    id 'java-library'
    id 'com.github.johnrengelman.shadow' version '5.2.0'
    id 'maven-publish'
}

group = 'com.acme'
version = '1.0.0'

repositories {
    jcenter()
}

java {
   sourceCompatibility = JavaVersion.VERSION_1_8
   targetCompatibility = JavaVersion.VERSION_1_8
}


dependencies {
    api 'org.apache.commons:commons-math3:3.6.1'
    implementation 'com.google.guava:guava:28.0-jre'
    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.5.1'
    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.5.1'
}

configurations {
   fatJarRuntimeElements {
      canBeResolved = false
      canBeConsumed = true
      attributes {
         attribute(Usage.USAGE_ATTRIBUTE, objects.named(Usage, Usage.JAVA_RUNTIME))
         attribute(Category.CATEGORY_ATTRIBUTE, objects.named(Category, Category.LIBRARY))
         attribute(LibraryElements.LIBRARY_ELEMENTS_ATTRIBUTE, objects.named(LibraryElements, LibraryElements.JAR))
         attribute(Bundling.BUNDLING_ATTRIBUTE, objects.named(Bundling, Bundling.EMBEDDED)) // means no relocation of packages
         attribute(TargetJvmVersion.TARGET_JVM_VERSION_ATTRIBUTE, 8)
      }
      outgoing.artifact(shadowJar)
   }
}

components.java {
   addVariantsFromConfiguration(configurations.fatJarRuntimeElements) {
      mapToOptional() // make it a Maven optional dependency
   }
}

test {
    useJUnitPlatform()
}

publishing {
   repositories {
      maven {
         url "${buildDir}/repo"
      }
   }
   publications {
       maven(MavenPublication) {
          from components.java
       }
   }
}

generated-gradle.module

{
  "formatVersion": "1.1",
  "component": {
    "group": "com.acme",
    "module": "shadow-example",
    "version": "1.0.0",
    "attributes": {
      "org.gradle.status": "release"
    }
  },
  "createdBy": {
    "gradle": {
      "version": "6.0.1",
      "buildId": "c6wz7vnfqzhatcvyuxk6cysfwy"
    }
  },
  "variants": [
    {
      "name": "apiElements",
      "attributes": {
        "org.gradle.category": "library",
        "org.gradle.dependency.bundling": "external",
        "org.gradle.jvm.version": 8,
        "org.gradle.libraryelements": "jar",
        "org.gradle.usage": "java-api"
      },
      "dependencies": [
        {
          "group": "org.apache.commons",
          "module": "commons-math3",
          "version": {
            "requires": "3.6.1"
          }
        }
      ],
      "files": [
        {
          "name": "shadow-example-1.0.0.jar",
          "url": "shadow-example-1.0.0.jar",
          "size": 838,
          "sha512": "b2e5da173e25217aa203b6953e935d354bf62425088aaeba22a0dff5a09b5000c80a116225e271b7ab5c6d916de0a4c7023450b6137d23b43894a2395efcb61e",
          "sha256": "cd9772b053a92a43de4194213e5b8ea6da064999c96f8b6067661b797e2c160b",
          "sha1": "9fb03a0a562eba278391942fb4956f2977b165b3",
          "md5": "16d42814a37c111c0b285d5742672cf5"
        }
      ]
    },
    {
      "name": "runtimeElements",
      "attributes": {
        "org.gradle.category": "library",
        "org.gradle.dependency.bundling": "external",
        "org.gradle.jvm.version": 8,
        "org.gradle.libraryelements": "jar",
        "org.gradle.usage": "java-runtime"
      },
      "dependencies": [
        {
          "group": "com.google.guava",
          "module": "guava",
          "version": {
            "requires": "28.0-jre"
          }
        },
        {
          "group": "org.apache.commons",
          "module": "commons-math3",
          "version": {
            "requires": "3.6.1"
          }
        }
      ],
      "files": [
        {
          "name": "shadow-example-1.0.0.jar",
          "url": "shadow-example-1.0.0.jar",
          "size": 838,
          "sha512": "b2e5da173e25217aa203b6953e935d354bf62425088aaeba22a0dff5a09b5000c80a116225e271b7ab5c6d916de0a4c7023450b6137d23b43894a2395efcb61e",
          "sha256": "cd9772b053a92a43de4194213e5b8ea6da064999c96f8b6067661b797e2c160b",
          "sha1": "9fb03a0a562eba278391942fb4956f2977b165b3",
          "md5": "16d42814a37c111c0b285d5742672cf5"
        }
      ]
    },
    {
      "name": "fatJarRuntimeElements",
      "attributes": {
        "org.gradle.category": "library",
        "org.gradle.dependency.bundling": "embedded",
        "org.gradle.jvm.version": 8,
        "org.gradle.libraryelements": "jar",
        "org.gradle.usage": "java-runtime"
      },
      "files": [
        {
          "name": "shadow-example-1.0.0-all.jar",
          "url": "shadow-example-1.0.0-all.jar",
          "size": 5146288,
          "sha512": "32af947065bcaa341d36033b00d94c267a44256fede08f570a479ec6415cb31ba31ec41ad6a0b51d37f1b3631e98b2960764d2d7ba709f29bad57e3519b5c3b9",
          "sha256": "4b746b2f8a1098f9441e20037ec8fd4ec5467023732d9e93d09d0a632c8e2b6c",
          "sha1": "4fc29a2f15a3ed7ea0b84ecdb17938777376cbe2",
          "md5": "271b1bd9a7c1a73e0e7f06516e8afc90"
        }
      ]
    }
  ]
}