主dex类的划分规则

执行task的入口代码：

// ---------
// create the transform that's going to take the code and the proguard keep list
// from above and compute the main class list.
Transform multiDexTransform;
if (usingIncrementalDexing(variantScope)) {
    if (projectOptions.get(BooleanOption.ENABLE_D8_MAIN_DEX_LIST)) {
        multiDexTransform = new D8MainDexListTransform(variantScope);
    } else {
        multiDexTransform =
                new MainDexListTransform(variantScope, extension.getDexOptions());
    }
} else {
    //创建MultiDexTransform
    multiDexTransform = new MultiDexTransform(variantScope, extension.getDexOptions());
}
multiDexClassListTask =
        transformManager.addTransform(taskFactory, variantScope, multiDexTransform);
multiDexClassListTask.ifPresent(variantScope::addColdSwapBuildTask);