More on nulls in Java.

This work remove nulls from Java; the work I mentioned earlier retains null
references and adds a never-null reference types.

  http://www.wisdomandwonder.com/link/1788/putting-java'ss-null-in-its-place

This url might not work because the apostrophe is a Unicode character (code
point) and might get munged along the way from here to there.  Here's

  http://www.ccs.neu.edu/scheme/pubs/dissertation-cobbe.pdf

the link to the dissertation (171 pages).