question: @ Override public void exceptionCaught ( IoSession session , Throwable cause ) { final IoSessionInputStream in = ( IoSessionInputStream ) session . getAttribute ( KEY_IN ) ; IOException e = null ; if ( cause instanceof StreamIoException ) { e = ( IOException ) cause . getCause ( ) ; } else if ( cause instanceof IOException ) { e = ( IOException ) cause ; } if ( e != null && in != null ) { in . throwException ( e ) ; } else { LOGGER . warn ( "Unexpected exception." , cause ) ; session . close ( true ) ; } }
target:  Forwards caught exceptions to input stream.