Truncates the entity, to which this channel is connected, to the given size.
If the given size is less than the current size then the entity is truncated, discarding any bytes beyond the new end. If the given size is greater than or equal to the current size then the entity is not modified. In either case, if the current position is greater than the given size then it is set to that size.
An implementation of this interface may prohibit truncation when
connected to an entity, typically a file, opened with the
|The new size, a non-negative byte count|
|If this channel was not opened for writing|
|If this channel is closed|
|If the new size is negative|
|If some other I/O error occurs|