自定义gradle插件时报错：Tasks can only be created using the Gradle API or DSL

自定义Gradle插件时，需要混淆jar文件，想当然的就去实例化 ProGuardTask

class MyCustomPlugin extends Plugin<Project> {
    void apply(Project target) {
        // ...
        // 混淆
        ProGuardTask proGuardJar= new ProGuardTask();
        proGuardJar.dependsOn(archiveClasses);
        proGuardJar.injars("build/libs/classes.jar");
        proGuardJar.outjars("build/release.jar");
        proGuardJar.configuration("proguard-rules.pro");
        // ...
    }
}

结果报错:
org.gradle.api.tasks.TaskInstantiationException: Task of type 'proguard.gradle.ProGuardTask' has been instantiated directly which is not supported. Tasks can only be created using the Gradle API or DSL.

正确的做法应该是调用 target.getTasks().create()创建一个任务对象

class MyCustomPlugin extends Plugin<Project> {
    void apply(Project target) {
        // ...
        // 混淆
        ProGuardTask proGuardJar = target.getTasks().create("proGuardJar", ProGuardTask.class);
        proGuardJar.dependsOn(archiveClasses);
        proGuardJar.injars("build/libs/classes.jar");
        proGuardJar.outjars("build/release.jar");
        proGuardJar.configuration("proguard-rules.pro");
        // ...
    }
}

使用ProGuardTask需要在build.gradle中添加依赖

dependencies {
    implementation gradleApi()
    implementation group: 'net.sf.proguard', name: 'proguard-gradle', version: '6.0.3'
}