Library projects cannot set applicationId. applicationId is set to 'com.example.mylogin' in default
在导入一个项目时，提示“Error:Library projects cannot set applicationId. applicationId is set to ‘com.xxx.yyy’ in default config.”，显然，library的build.gradle中不能指定“applicationId”。
Execution failed for task ':app:checkDebugDuplicateClasses'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckDuplicatesRunnable
