According to Eclipse, why is the standard jar file extension ".jar;*.zip"?

Question

I tried to export a runnable Jar, and Eclipse said:

You have used the extension ".jar" at the end of the name. The standard extension is ".jar;*.zip".

You can choose to use the standard extension instead.

[Use .jar;*.zip]                     [Cancel]       [Use .jar]

(See screenshot below.)

Is there some sort of massive misunderstanding on my part here? Because ".jar;*.zip" really does not sound like a file extension to me. Why would it (Eclipse Luna 4.4.0) not want me to save it (a standard Java program) as a .jar? Just to be clear, it lets me and everything works, but why the warning?

Answer 1

I have submitted a bug report here.