Could not get unknown property 'assembleRelease' for project ':app' of type org.gradle.api.Project.

Could not get unknown property 'assembleRelease' for project ':app' of type org.gradle.api.Project.

解决方法：

assembleRelease.finalizedBy(check) 
改为：

tasks.whenTaskAdded { task ->
    if (task.name == 'assembleRelease') {
        task.finalizedBy 'check'
    }
}