RFR(S): 8067471: Use private static final char[0] for empty Strings

[Ivan Gerasimov]

Hi Lev!

When you'll be preparing the final webrev, can you please also include a 
typo fix in it?

s/dstbegin/dstBegin/g

This typo is found in a couple of places in String.java.

Sincerely yours,
Ivan