<Swing Dev> Replace concat String to append in StringBuilder parameters

[Ivan Gerasimov]

Hi Max!

> The core part is updated again at
>
>    http://cr.openjdk.java.net/~weijun/8055723/core/webrev.03/

Can you please revert changes to 
src/java.base/share/classes/sun/net/www/MimeEntry.java, as they're 
conflicting with the fix for JDK-8054714?

Apologizing for adding you more work.

Sincerely yours,
Ivan