8141652 : Rename methods Objects.nonNullElse* to requireNonNullElse*

[Roger Riggs]

Please review the renaming of java.util.Object methods, the new method 
names are:
     public static <T> T requireNonNullElse(T obj, T defaultObj);
     public static <T> T requireNonNullElseGet(T obj, Supplier<? extends 
T> supplier);

The only remaining possible gotcha for developers is the 
requireNonNull(T, String)
method that might be confused with requireNonNullElse(T, T).  The longer 
name is probably the one you want.
If you see a value that looks like an exception string, you've got the 
wrong method.

To validate some of the uses, I visually scanned src/java.base looking 
expressions of the pattern   (e1 != null) ? e1 : e2
Most uses of the ternary operator involve either primitive types or 
conditions other than != null;
quite a few involved returning null and so were not appropriate to be 
converted.

10 files contained relevant expressions:
  - 2 should be using Objects.toString() to provide a default value for 
a String.
  - 2 can use the requireNonNullElseGet form to delay evaluating the 
alternative value.
      (2 others were too early in the boot cycle to use lambda).
  - The rest followed the expected pattern; though checking if throwing 
an exception was extra work.

Please review and comment.

Webrev:
http://cr.openjdk.java.net/~rriggs/webrev-require-non-null-8141652/

Thanks for the detailed evaluation and discussion.

Roger