Which class or interface do the build processes start with in the system?

In Android, the build process usually starts with a class or interface that manages the build configuration — this is Gradle and its scripts (build.gradle).

Gradle is a build automation system that uses scripts written in Groovy or Kotlin DSL to define build tasks, dependencies, and configurations.

The main entry points into the build process are:

• The build.gradle (or build.gradle.kts) file — describes modules, dependencies, and tasks.
• The Gradle class and related APIs, which execute build tasks.

An example of starting a build from the command line:

gradle assembleDebug

Thus, the build process begins with Gradle and its configuration files.