groovy> dt = sdf.parse("12:15:06.09");
groovy> go

===> Thu Jan 01 12:15:06 EST 1970

groovy> print sdf.format(dt);
groovy> go
12:15:06.009
===> null

groovy> dt = sdf.parse("12:15:06.090");
groovy> print sdf.format(dt);
groovy> go
12:15:06.090