@Override
  protected Set<StepField> getUsedFields( final JsonInputMeta meta ) {
    Set<StepField> usedFields = new HashSet<>();
    if ( meta.isAcceptingFilenames() && StringUtils.isNotEmpty( meta.getAcceptingField() ) ) {
      final Set<String> inpusStepNames = getInputStepNames( meta, meta.getAcceptingField() );
      for ( final String inpusStepName : inpusStepNames ) {
        final StepField stepField = new StepField( inpusStepName, meta.getAcceptingField() );
        usedFields.add( stepField );
      }
    }
    return usedFields;
  }
@Test
  public void testGetUsedFields_fileNameFromField() throws Exception {
    when( meta.isAcceptingFilenames() ).thenReturn( true );
    when( meta.getAcceptingField() ).thenReturn( "filename" );
    Set<String> stepNames = new HashSet<>();
    stepNames.add( "previousStep" );

    Set<StepField> usedFields = analyzer.getUsedFields( meta );
    assertNotNull( usedFields );
    assertEquals( 1, usedFields.size() );
    StepField used = usedFields.iterator().next();
    assertEquals( "previousStep", used.getStepName() );
    assertEquals( "filename", used.getFieldName() );
  }