RFR(L): 8218628: Add detailed message to NullPointerException describing what is null.

[mark.reinhold at oracle.com]

2019/3/14 8:00:20 -0700, maurizio.cimadamore at oracle.com:
> I second what Mandy says.
> 
> First let me start by saying that this enhancement will be a great 
> addition to our platform; back in the days when I was teaching some Java 
> classes at the university, I was very aware of how hard it is to 
> diagnose a NPE for someone novel to Java programming.

Agreed!

> ...
> 
> I also think that the design space for such an enhancement is non 
> trivial, and would best be explored (and captured!) in a medium that is 
> something other than a patch. ...

Agreed, also.

Goetz -- if, per Mandy’s suggestion, you’re going to write something
up using the JEP template, might I suggest that you then submit it as
an actual JEP?  Giving visibility to, and recording, such design-space
explorations is one of the primary goals of the JEP process.

- Mark