build: replace deprecated Kotlin DSL property delegates

Gradle 9.6 deprecates all Kotlin DSL delegated-property extensions
(`by creating`, `by registering`, `by project`); they are scheduled for
removal in Gradle 10. Replace them with the explicit container API
(`create(name)`, `register(name)`) and `findProperty` across the build
scripts, the precompiled sign-base plugin, the examples, the sandbox,
and the plugin smoke test.

Closes #1207.

Note for reviewers: building the project on Gradle 9.6 still emits one
`by creating` warning, but it originates from the published
`dev.sigstore:sigstore-gradle-sign-plugin:2.2.0` used to self-sign the
build (build-logic/publishing/build.gradle.kts). It clears once that
bootstrap dependency is bumped to a release containing this fix. The
remaining `afterSuite`/`afterTest` warnings are pre-existing and
unrelated to this change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Vladimir Sitnikov <sitnikov.vladimir@gmail.com>

Author: vlsi

build-logic/jvm/src/main/kotlin/build-logic.build-info.gradle.kts

@@ -4,7 +4,7 @@ plugins {
     java
 }
 
-val generateBuildInfo by tasks.registering(BuildInfoTask::class) {
+val generateBuildInfo = tasks.register("generateBuildInfo", BuildInfoTask::class) {
     version.set(project.version.toString())
     genDir.set(project.layout.buildDirectory.dir("generated/buildinfo"))
 }

build-logic/jvm/src/main/kotlin/build-logic.dokka-javadoc.gradle.kts

@@ -11,7 +11,7 @@ java {
     }
 }
 
-val dokkaJar by tasks.registering(Jar::class) {
+val dokkaJar = tasks.register("dokkaJar", Jar::class) {
     group = LifecycleBasePlugin.BUILD_GROUP
     description = "Assembles a jar archive containing javadoc"
     from(tasks.dokkaGeneratePublicationJavadoc)

build-logic/publishing/src/main/kotlin/build-logic.depends-on-local-sigstore-java-repo.gradle.kts

@@ -7,13 +7,13 @@ plugins {
     java
 }
 
-val sigstoreJavaRuntime by configurations.creating {
+val sigstoreJavaRuntime = configurations.create("sigstoreJavaRuntime") {
     description = "declares dependencies that will be useful for testing purposes"
     isCanBeConsumed = false
     isCanBeResolved = false
 }
 
-val sigstoreJavaTestClasspath by configurations.creating {
+val sigstoreJavaTestClasspath = configurations.create("sigstoreJavaTestClasspath") {
     description = "sigstore-java in local repository for testing purposes"
     isCanBeConsumed = false
     isCanBeResolved = true

build-logic/publishing/src/main/kotlin/build-logic.depends-on-local-sigstore-maven-plugin-repo.gradle.kts

@@ -7,13 +7,13 @@ plugins {
     java
 }
 
-val sigstoreMavenPluginRuntime by configurations.creating {
+val sigstoreMavenPluginRuntime = configurations.create("sigstoreMavenPluginRuntime") {
     description = "declares dependencies that will be useful for testing purposes"
     isCanBeConsumed = false
     isCanBeResolved = false
 }
 
-val sigstoreMavenPluginTestClasspath by configurations.creating {
+val sigstoreMavenPluginTestClasspath = configurations.create("sigstoreMavenPluginTestClasspath") {
     description = "sigstore-maven-plugin in local repository for testing purposes"
     isCanBeConsumed = false
     isCanBeResolved = true

build-logic/publishing/src/main/kotlin/build-logic.publish-to-tmp-maven-repo.gradle.kts

@@ -1,11 +1,9 @@
-import org.gradle.kotlin.dsl.registering
-
 plugins {
     id("java-library")
     id("maven-publish")
 }
 
-val localRepoElements by configurations.creating {
+val localRepoElements = configurations.create("localRepoElements") {
     isCanBeConsumed = true
     isCanBeResolved = false
     description =
@@ -31,7 +29,7 @@ localRepoElements.outgoing.artifact(localRepoDir) {
     builtBy(tasks.named("publishAllPublicationsToTmp-mavenRepository"))
 }
 
-val cleanLocalRepository by tasks.registering(Delete::class) {
+val cleanLocalRepository = tasks.register("cleanLocalRepository", Delete::class) {
     description = "Clears local-maven-repo so timestamp-based snapshot artifacts do not consume space"
     delete(localRepoDir)
 }

build-logic/publishing/src/main/kotlin/build-logic.signing.gradle.kts

@@ -4,8 +4,8 @@ plugins {
 }
 
 signing {
-    val signingKey: String? by project
-    val signingPassword: String? by project
+    val signingKey = project.findProperty("signingKey") as String?
+    val signingPassword = project.findProperty("signingPassword") as String?
     useInMemoryPgpKeys(signingKey, signingPassword)
 }
 

build.gradle.kts

@@ -14,7 +14,7 @@ allprojects {
     version = calculatedVersion
 }
 
-val parameters by tasks.registering {
+val parameters = tasks.register("parameters") {
     group = HelpTasksPlugin.HELP_GROUP
     description = "Displays build parameters (i.e. -P flags) that can be used to customize the build"
     dependsOn(gradle.includedBuild("build-logic").task(":build-parameters:parameters"))

examples/hello-world/build.gradle.kts

@@ -33,8 +33,8 @@ publishing {
 
 // PGP signing setup for the purposes of this example.
 signing {
-    val signingKey: String? by project
-    val signingPassword: String? by project
+    val signingKey = project.findProperty("signingKey") as String?
+    val signingPassword = project.findProperty("signingPassword") as String?
     useInMemoryPgpKeys(signingKey, signingPassword)
     sign(publishing.publications["maven"])
 }

sandbox/gradle-sign-file/build.gradle.kts

@@ -18,14 +18,14 @@ dependencies {
     // sigstoreClientClasspath("dev.sigstore:sigstore-java:0.1.0")
 }
 
-val hello by tasks.registering(WriteProperties::class) {
+val hello = tasks.register("hello", WriteProperties::class) {
     group = LifecycleBasePlugin.BUILD_GROUP
     description = "Generates a sample $name.properties file to sign"
     destinationFile.set(layout.buildDirectory.file("props/$name.properties"))
     property("hello", "world")
 }
 
-val signFile by tasks.registering(SigstoreSignFilesTask::class) {
+val signFile = tasks.register("signFile", SigstoreSignFilesTask::class) {
     group = LifecycleBasePlugin.BUILD_GROUP
     description = "Signs file via Sigstore"
     signFile(hello.map { it.destinationFile.get().asFile })

sigstore-gradle/sigstore-gradle-sign-base-plugin/src/main/kotlin/dev.sigstore.sign-base.gradle.kts

@@ -30,7 +30,7 @@ gradle.sharedServices.registerIfAbsent(SigstoreSigningService.SERVICE_NAME, Sigs
     }
 }
 
-val sigstoreClient by configurations.creating {
+val sigstoreClient = configurations.create("sigstoreClient") {
     description = "Declares sigstore client dependencies"
     isCanBeResolved = false
     isCanBeConsumed = false
@@ -41,7 +41,7 @@ val sigstoreClient by configurations.creating {
     }
 }
 
-val sigstoreClientClasspath by configurations.creating {
+val sigstoreClientClasspath = configurations.create("sigstoreClientClasspath") {
     description = "Resolves Sigstore dependencies"
     isCanBeResolved = true
     isCanBeConsumed = false