question: private void addUnbuffered ( T elem ) { unbufferedElements . add ( elem ) ; if ( unbufferedElements . size ( ) == bufferSize ) { Collections . sort ( unbufferedElements , compareFn ) ; buffers . add ( new QuantileBuffer < T > ( unbufferedElements ) ) ; unbufferedElements = Lists . newArrayListWithCapacity ( bufferSize ) ; collapseIfNeeded ( ) ; } }
target:  Add a new buffer to the unbuffered list, creating a new buffer and collapsing if needed.