Causes a single submitted value to be changed to a list containing 1 item.
Solves an uncommon problem with a
Repeatable block with
disabled, when manually increasing the
repeat count after the form was
submitted with only a single value for each of the Repeatables fields.
If these circumstances, when rendered, every repeated field would have the
initially-submitted value as its default.
Using this filter, and setting
render_processed_value to true will
ensure that only the first repetition of each field will have the submitted
value as its default; all subsequent repetitions will have no default value.