close method
override
    Closes the sink.
The add method must not be called after this method.
Calling this method more than once is allowed, but does nothing.
Implementation
void close() {
  _sink.close();
}Closes the sink.
The add method must not be called after this method.
Calling this method more than once is allowed, but does nothing.
void close() {
  _sink.close();
}