Android Studio: "Use default gradle wrapper" vs. "Use customizable gradle wrapper"

See the IntelliJ IDEA help here:

• Using the default gradle wrapper means that Gradle controls the version number
• Using the customizable gradle wrapper means that IDEA controls the version number of the gradle wrapper.

The version number is stored in gradle/wrapper/gradle-wrapper.properties. So when you choose "using the customizable gradle wrapper" each time you are opening the project with IDEA, it will change the property file to adjust the wrapper version you specified in the IDEA project.

For the sake of repeatable builds (even on your continuous build server which doesn't run IDEA) let Gradle control the version number and use the default gradle wrapper.

You can set the version number which is used by Gradle inside your build.gradle with

// needs at least Gradle V1.7
wrapper {
    gradleVersion = '2.2.1'
}

or

// works with every Gradle version
task wrapper(type: Wrapper) {
    gradleVersion = '2.2.1'
}

Remark: don't forget that this configuration is only used for the generation of the wrapper. To activate it, you have to execute the generation with gradlew wrapper. This tasks updates the gradle-wrapper.properties which is used afterwards for all wrapper executions.