Sets the default value within the holder. If value is null then holder won't have a
default value anymore. To set a default value to null, then pass a #GValue created using
gda.global.valueNewNull.
NOTE: the default value does not need to be of the same type as the one required by holder.
Sets the default value within the holder. If value is null then holder won't have a default value anymore. To set a default value to null, then pass a #GValue created using gda.global.valueNewNull.
NOTE: the default value does not need to be of the same type as the one required by holder.