Expression Language documentation should be clarified for isEmpty and allAttributes

The documentation for isEmpty and allAttributes should be reviewed for correctness and clarity as pointed out by a member of the mailing list.

From the mailing list:

From: Paul Nahay <pnahay@sprynet.com>
Subject: Errors in your Documentation
Date: March 22, 2016 at 5:52:10 AM PDT
To: dev@nifi.apache.org
Cc: Jonathan Wood <jkwood42@gmail.com>
Reply-To: dev@nifi.apache.org
Reply-To: Paul Nahay <pnahay@sprynet.com>

I'm looking at:

https://nifi.apache.org/docs/nifi-docs/html/expression-language-guide.html

isEmpty
Description: The isEmpty function returns true if the Subject is null or contains only white-space (new line, carriage return, space, tab), false otherwise.

This logically implies that isEmpty returns FALSE if the Subject contains NO CHARACTERS AT ALL (not even white-space). This makes no sense at all.

allAttributes
Description: Checks to see if any of the given attributes, match the given condition.

Hopefully you actually mean "all", not "any".

What's funny here is that THESE TWO functions were the ones I initially needed, and your documentation has errors for BOTH of them. I'll expect then to find more errors in your documentation, and will report them to you as I find them.

Feedback confirming the errors will be appreciated.