Review messages used in Assert calls

[philwebb]

Currently we tend to call assert with message like this:

Assert.notNull(fooBar, "FooBar must not be null");

Framework actually uses two different styles of message which mean slightly different things. A message "FooBar must not be null" refers to a type called FooBar. A message "'fooBar' must not be null" refers to the parameter or property name and is used when there is no useful explicit type.

[jjsfernandez]

Hi @philwebb, can i work on this issue?

[philwebb]

Sorry for the late reply @JosejeSinohui. This one is likely to touch a lot of files so I think it's best if one of the core team take care of it since we'll need to coordinate around other work.

[izeye]

This seems to be resolved in #43780.