question: public static RotateStream create ( Path path ) { synchronized ( _streams ) { WeakReference < RotateStream > ref = _streams . get ( path ) ; RotateStream stream = ref != null ? ref . get ( ) : null ; if ( stream == null ) { stream = new RotateStream ( path ) ; _streams . put ( path , new WeakReference < > ( stream ) ) ; } return stream ; } }
target:  Returns the rotate stream corresponding to this path