Cannot add task ‘wrapper’ as a task with that name already exists

You can also update

task wrapper(type: Wrapper) {
    gradleVersion = '4.4'    
    distributionUrl = distributionUrl.replace("bin", "all")
}

to

wrapper {
    gradleVersion = '4.4'
    distributionUrl = distributionUrl.replace("bin", "all")
}

As

Overriding built-in tasks deprecated in 4.8 now produces an error.

Attempting to replace a built-in task will produce an error similar to the following:

Cannot add task ‘wrapper’ as a task with that name already exists.

see the last paragraph of Tasks & properties:
https://docs.gradle.org/5.2.1/userguide/upgrading_version_4.html

and Customizing the Wrapper task:
https://docs.gradle.org/5.2.1/userguide/gradle_wrapper.html#customizing_wrapper