If you take advantage of the option in the LGPL to put a
particular version of this library under the GPL, the author(s)
would regard it as polite if you would put any direct
modifications under the LGPL as well.  If you distribute this
library with direct modifications under the LGPL, we would also
regard it as polite if you would include a copy of this file
with your distribution, and mention it as part of the license
notice near the beginning of the library source.  A "direct
modification" is one that enhances or extends the library in
line with its original concept, as opposed to developing a
distinct application or library which might use it.

This is only a request, not a legal requirement.