question: private void ensureResponse ( ) throws IOException { if ( m_response == null ) { try { final boolean traceEnabled = log . isTraceEnabled ( ) ; final long start = traceEnabled ? System . currentTimeMillis ( ) : 0 ; m_response = get ( queryTimeoutMillis , TimeUnit . MILLISECONDS ) ; if ( traceEnabled ) log . trace ( "Response in " + ( System . currentTimeMillis ( ) - start ) + "ms" ) ; } catch ( InterruptedException | TimeoutException | ExecutionException e ) { throw new IOException ( e ) ; } } }
target:  Blocks (up to a timeout) for the response to arrive (http status code, etc.)