A simple solution for [] access that can trivially be added to List and Map.

[Paulo Levi]

Just speaking out, me a "normal" java programmer, don't really care about
[]. I like the idea of extension methods much more especially if they can't
be invoked directly, since, they can serve as a bridge between a
hypothetical java 7 and a hypothetical java 8 with the extended interfaces
(List, CharSequence etc), so that then, those extensions methods become
no-ops.

Also could you please make a super-interface of both StringBuilder and
StringBuffer? There are lot of places on the jdk using StringBuffer when
they should use StringBuilder, but can't be changed because they are public
methods.