A TrivialTask is a task that has been done so many times that it is performed essentially by rote -- often using automated tools. The effort to complete such a task is highly predictable.
Sometimes a TrivialTask can take milliseconds -- and sometimes months. TrivialTask is not a synonym for "instantaneous" (although it is a synonym for "easy". The phrase characterizes the predictability and effort of the task, not its duration.
In this context, it is used in contrast to "StraightForwardTask" or "InventionRequiredTask".
Generating the read and write accessors of the attributes of a type is a TrivialTask -- and takes milliseconds using a reasonable IDE. Generating an index for a large full-text database is another TrivialTask -- and can take months, depending on the system resources available and the size of the database.