### Question:
SubtransExecutor { public Optional<Result> execute( List<RowMetaAndData> rows ) throws KettleException { if ( rows.isEmpty() || stopped ) { return Optional.empty(); } Trans subtrans = this.createSubtrans(); running.add( subtrans ); parentTrans.addActiveSubTransformation( subTransName, subtrans ); passParametersToTrans( subtrans, rows.get( 0 ) ); Result result = new Result(); result.setRows( rows ); subtrans.setPreviousResult( result ); subtrans.prepareExecution( this.parentTrans.getArguments() ); List<RowMetaAndData> rowMetaAndData = new ArrayList<>(); subtrans.getSteps().stream() .filter( c -> c.step.getStepname().equalsIgnoreCase( subStep ) ) .findFirst() .ifPresent( c -> c.step.addRowListener( new RowAdapter() { @Override public void rowWrittenEvent( RowMetaInterface rowMeta, Object[] row ) { rowMetaAndData.add( new RowMetaAndData( rowMeta, row ) ); } } ) ); subtrans.startThreads(); subtrans.waitUntilFinished(); updateStatuses( subtrans ); running.remove( subtrans ); Result subtransResult = subtrans.getResult(); subtransResult.setRows( rowMetaAndData ); return Optional.of( subtransResult ); } SubtransExecutor( String subTransName, Trans parentTrans, TransMeta subtransMeta, boolean shareVariables,
                           TransExecutorParameters parameters, String subStep ); Optional<Result> execute( List<RowMetaAndData> rows ); void stop(); Map<String, StepStatus> getStatuses(); Trans getParentTrans();  }### Answer:
@Test public void testRunningZeroRowsIsEmptyOptional() throws Exception { SubtransExecutor subtransExecutor = new SubtransExecutor( "subtransname", null, null, false, null, "" ); Optional<Result> execute = subtransExecutor.execute( Collections.emptyList() ); assertFalse( execute.isPresent() ); }