JLS 3.10.4 -- Unicode escape for apostrophe

[Alex Buckley]

The following issue was raised on the java-se-spec-comments list:

https://mail.openjdk.java.net/pipermail/java-se-spec-comments/2019-October/000004.html

"In the Java Language Specification JSE13 Edition, 3.10.4, Character 
Literals, the next to last paragraph needs an additional sentence: 
"Finally, it is not possible to write '\u0027' for a character literal 
containing an apostrophe (').".

To be helpful, and to align with a similar sentence in 3.10.5, 3.10.4 
should indeed add the sentence above to the informative paragraph which 
currently ends "Instead, use '\r'."

Alex