Google Script Library: Project Key deprecated?

Question

I am creating a library in the Google Script editor to use functions for different documents. For that I import the project key from the main project to other scripts.

However I noticed it says Project Key (deprecated) now, which was not there before. Does anyone know what this means?

Answer 1

Found the answer on this blog post:
https://plus.google.com/+EricKoleda/posts/K7P7pHefXir

What I want to make clear: we have no plans to turn off or disable the use of project keys. All your code that uses project keys will continue to work for the foreseeable future, and any plans to change that will be formally announced far in advance. Deprecation merely means that we no longer encourage their use, and instead recommend people use the Script ID.

Answer 2

I would like to also note that even though use of the ScriptID is not specifically mentioned when attempting to add a library, for example:

Enter the library's project key (found under File > Project Properties). Make sure you have permissions to access the library or its containing spreadsheet.

If you enter the ScriptID regardless and press the Select button, it works.