Program: 136604
Project: 136604
Buggy source:
@Override public void fillContextMenu(IMenuManager menu){
  if (!isShowMenu()) {
    return;
  }
  TreeSelection currentSelection=((TreeSelection)this.getContext().getSelection());
  Object firstElement=currentSelection.getFirstElement();
  if (firstElement instanceof DBTableRepNode) {
    DBTableRepNode node=(DBTableRepNode)firstElement;
    semanticDiscoveryAction=new SemanticDiscoveryAction(node.getTdTable());
  }
 else   if (firstElement instanceof DBViewRepNode) {
    DBViewRepNode node=(DBViewRepNode)firstElement;
    semanticDiscoveryAction=new SemanticDiscoveryAction(node.getTdView());
  }
 else   if (firstElement instanceof DFTableRepNode) {
    DFTableRepNode node=(DFTableRepNode)firstElement;
    semanticDiscoveryAction=new SemanticDiscoveryAction(node.getMetadataTable());
  }
 else {
    Set<String> currentTableSet=new HashSet<String>();
    MetadataTable createTable=ConnectionFactory.eINSTANCE.createMetadataTable();
    List<String> filterNames=new ArrayList<String>();
    Iterator<Object> columnIterator=currentSelection.iterator();
    while (columnIterator.hasNext()) {
      Object columnNode=columnIterator.next();
      MetadataColumn metadataColumn=null;
      if (DBColumnRepNode.class.isInstance(columnNode)) {
        metadataColumn=((DBColumnRepNode)columnNode).getTdColumn();
        createTable=ColumnHelper.getColumnOwnerAsMetadataTable(metadataColumn);
      }
 else       if (DFColumnRepNode.class.isInstance(columnNode)) {
        metadataColumn=((DFColumnRepNode)columnNode).getMetadataColumn();
        createTable=ColumnHelper.getColumnOwnerAsMetadataTable(metadataColumn);
      }
 else {
        return;
      }
      currentTableSet.add(ResourceHelper.getUUID(createTable));
      if (currentTableSet.size() > 1) {
        return;
      }
      filterNames.add(metadataColumn.getName());
    }
    MetadataTable metadataTableWithFilter=new MetadataTableWithFilter(filterNames,createTable);
    semanticDiscoveryAction=new SemanticDiscoveryAction(metadataTableWithFilter);
  }
  menu.add(semanticDiscoveryAction);
}

Fixed version (ground truth):
@Override public void fillContextMenu(IMenuManager menu){
  if (!isShowMenu()) {
    return;
  }
  TreeSelection currentSelection=((TreeSelection)this.getContext().getSelection());
  Object firstElement=currentSelection.getFirstElement();
  boolean selectedMoreThanOne=currentSelection.size() > 1;
  if (selectedMoreThanOne || firstElement instanceof ColumnRepNode) {
    Set<String> currentTableSet=new HashSet<String>();
    MetadataTable createTable=ConnectionFactory.eINSTANCE.createMetadataTable();
    List<String> filterNames=new ArrayList<String>();
    Iterator<Object> columnIterator=currentSelection.iterator();
    while (columnIterator.hasNext()) {
      Object columnNode=columnIterator.next();
      MetadataColumn metadataColumn=null;
      if (DBColumnRepNode.class.isInstance(columnNode)) {
        metadataColumn=((DBColumnRepNode)columnNode).getTdColumn();
        createTable=ColumnHelper.getColumnOwnerAsMetadataTable(metadataColumn);
      }
 else       if (DFColumnRepNode.class.isInstance(columnNode)) {
        metadataColumn=((DFColumnRepNode)columnNode).getMetadataColumn();
        createTable=ColumnHelper.getColumnOwnerAsMetadataTable(metadataColumn);
      }
 else {
        return;
      }
      currentTableSet.add(ResourceHelper.getUUID(createTable));
      if (currentTableSet.size() > 1) {
        return;
      }
      filterNames.add(metadataColumn.getName());
    }
    MetadataTable metadataTableWithFilter=new MetadataTableWithFilter(filterNames,createTable);
    semanticDiscoveryAction=new SemanticDiscoveryAction(metadataTableWithFilter);
  }
 else {
    if (firstElement instanceof DBTableRepNode) {
      DBTableRepNode node=(DBTableRepNode)firstElement;
      semanticDiscoveryAction=new SemanticDiscoveryAction(node.getTdTable());
    }
 else     if (firstElement instanceof DBViewRepNode) {
      DBViewRepNode node=(DBViewRepNode)firstElement;
      semanticDiscoveryAction=new SemanticDiscoveryAction(node.getTdView());
    }
 else     if (firstElement instanceof DFTableRepNode) {
      DFTableRepNode node=(DFTableRepNode)firstElement;
      semanticDiscoveryAction=new SemanticDiscoveryAction(node.getMetadataTable());
    }
  }
  menu.add(semanticDiscoveryAction);
}