[Konvert] Convert AssertJGeneratorExtension class to Kotlin (#42)

This is a straight conversion with no functionality changes.

Extracted from #29.

Author: Nava2

src/main/groovy/org/assertj/generator/gradle/tasks/config/AssertJGeneratorExtension.groovy

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2023. assertj-generator-gradle-plugin contributors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+package org.assertj.generator.gradle.tasks.config
+
+import org.assertj.assertions.generator.AssertionsEntryPointType
+import org.gradle.api.Action
+import org.gradle.api.Project
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.model.ObjectFactory
+import org.gradle.api.tasks.SourceSet
+import org.gradle.kotlin.dsl.newInstance
+import javax.inject.Inject
+
+/**
+ * Defines useful parameters and options for configuration of the
+ * {@link org.assertj.assertions.generator.AssertionGenerator}.
+ */
+open class AssertJGeneratorExtension @Inject internal constructor(
+  objects: ObjectFactory,
+  project: Project,
+  sourceSet: SourceSet
+) {
+  /**
+   * Generate generating Soft Assertions entry point class.
+   * @return templates value, never {@code null}
+   */
+  val templates: Templates = objects.newInstance()
+
+  /**
+   * Method used for improving configuration DSL
+   * @return {@code this}
+   */
+  fun templates(action: Action<in Templates>): AssertJGeneratorExtension {
+    action.execute(templates)
+    return this
+  }
+
+  /**
+   * Contains configuration regarding the "Assertion" entry point class generation. By default, only the "standard"
+   * version is generated.
+   *
+   * See the
+   * [assertj generator docs](http://joel-costigliola.github.io/assertj/assertj-assertions-generator.html#generated-entry-points)
+   * on entry points.
+   *
+   * @return entry points configuration
+   */
+  @Suppress("MaxLineLength")
+  val entryPoints: EntryPointGeneratorOptions = objects.newInstance()
+
+  /**
+   * Helper method for simplifying usage in build scripts
+   * @param values Values to set
+   */
+  fun setEntryPoints(vararg rest: AssertionsEntryPointType) {
+    this.entryPoints.only(rest = rest)
+  }
+
+  /**
+   * Exposed for build scripts
+   * @param values String values passed from a build script
+   */
+  fun setEntryPoints(values: Collection<String>) {
+    entryPoints.only(rest = values.toTypedArray())
+  }
+
+  /**
+   * Used to change "entry point" class generation.
+   *
+   * @param closure Applied via {@link org.gradle.util.ConfigureUtil#configure(Closure, Object)}
+   * @return this
+   */
+  fun entryPoints(action: Action<in EntryPointGeneratorOptions>): AssertJGeneratorExtension {
+    action.execute(entryPoints)
+    return this
+  }
+
+  /**
+   * The root directory where all generated files will be placed (within sub-folders for packages).
+   * @return File the output directory for {@code sourceSet}
+   */
+  val outputDir: DirectoryProperty = objects.directoryProperty()
+    .convention(project.layout.buildDirectory.dir("generated-src/${sourceSet.name}-test/java"))
+
+  /**
+   * Flag specifying whether to generate hierarchical assertions. The default is false.
+   * @return true if generating hierarchical
+   */
+  var hierarchical = false
+
+  /**
+   * Skip generating classes, handy way to disable temporarily.
+   * @return true if skipping this set
+   */
+  var skip = false
+}