Implemente createBundle task in Gradle to create GitHub release bundle

The bundle jars which are uploaded to GitHub include all of the
artifacts including the signing files with the artifacts.

Author: DenWav

buildSrc/src/main/kotlin/b2sdk.gradle.kts

@@ -2,6 +2,7 @@
 // License https://www.backblaze.com/using_b2_code.html
 
 import org.gradle.api.credentials.PasswordCredentials
+import org.gradle.api.publish.internal.PublicationInternal
 
 plugins {
     java
@@ -139,25 +140,33 @@ publishing {
     }
 }
 
-// Don't configure signing unless this is present
 val sonatypeUsername = findProperty("sonatypeUsername")
 val sonatypePassword = findProperty("sonatypePassword")
 
 val gpgSigningKey = System.getenv("GPG_SIGNING_KEY")
 val gpgPassphrase = System.getenv("GPG_PASSPHRASE")
 
-if (sonatypeUsername != null && sonatypePassword != null) {
-    signing {
-        setRequired {
-            gradle.taskGraph.hasTask("publishToSonatype")
-        }
+signing {
+    setRequired {
+        gradle.taskGraph.hasTask("publishToSonatype") || gradle.taskGraph.hasTask("createBundle")
+    }
 
-        if (gpgSigningKey != null && gpgPassphrase != null) {
-            useInMemoryPgpKeys(gpgSigningKey, gpgPassphrase)
-        } else {
-            useGpgCmd()
-        }
+    if (gpgSigningKey != null && gpgPassphrase != null) {
+        useInMemoryPgpKeys(gpgSigningKey, gpgPassphrase)
+    } else {
+        useGpgCmd()
+    }
 
-        sign(publishing.publications["maven"])
+    sign(publishing.publications["maven"])
+}
+
+tasks.register<Jar>("createBundle") {
+    archiveBaseName.set("bundle-for-${project.name}")
+    from((project.publishing.publications["maven"] as PublicationInternal<*>).publishableArtifacts.files) {
+        rename {
+            it
+                .replace("pom-default.xml", "${project.name}-${project.version}.pom")
+                .replace("module.json", "${project.name}-${project.version}.module")
+        }
     }
 }