This is an excerpt of my initial reaction:
“Hi Steven,

I’m sorry that you’re bumping into this block.

I agree that documentation is lacking in some areas, mostly for code
that was initiated earlier than three years ago. We’ve tried to fill
in the Javadocs holes and I think that in the areas that we did
cover, we’re doing an excellent job at this. In contrast to what
you’re saying, there have been many compliments about the quality of
the current documentation (even though there are lacunas). Also,
since three years, no public APIs get committed anymore without
Javadocs. Additionally, as you probably saw, each release contains
extremely detailed release notes with examples that are afterwards
aggregated in the wiki’s cookbook. I think that there is no open-
source project out there that does this as extensively. Stating that
documentation is an afterthought thus feels really very harsh to me.
A project with the momentum of Spring, with their amount of
contributors and commercial companies behind it, is of course able to
provide a lot more in terms of books and user guides. There’s only so
much that a small team of motivated developers can do for free in
their spare time. However, if you do feel that some areas need to be
improved quicker, you’re always welcome to contribute to the effort
and document your findings either in articles or Javadoc additions
that you can send to me as patches.

… more …”