Program: 25119
Project: 25119
Buggy source:
/** 
 * Checks whether the given column reference corresponds to a selected item (column or an expression with an alias) or to an existing column.
 * @param colRef			The column reference which must be checked.
 * @param select			The SELECT clause of the ADQL query.
 * @param dbColumns			The list of all available {@link DBColumn}s.
 * @return 					The corresponding {@link DBColumn} if this reference is actually the name of a column, <i>null</i> otherwise.
 * @throws ParseException	An {@link UnresolvedColumnException} if the given column can't be resolvedor an  {@link UnresolvedTableException} if its table reference can't be resolved.
 * @see ClauseSelect#searchByAlias(String)
 * @see #resolveColumn(ADQLColumn,SearchColumnList)
 */
protected DBColumn checkColumnReference(final ColumnReference colRef,final ClauseSelect select,final SearchColumnList dbColumns) throws ParseException {
  if (colRef.isIndex()) {
    int index=colRef.getColumnIndex();
    if (index > 0 && index <= select.size()) {
      SelectItem item=select.get(index - 1);
      if (item.getOperand() instanceof ADQLColumn)       return ((ADQLColumn)item.getOperand()).getDBLink();
 else       return null;
    }
 else     throw new ParseException("String_Node_Str" + index + "String_Node_Str"+ select.size()+ "String_Node_Str");
  }
 else {
    ADQLColumn col=new ADQLColumn(colRef.getColumnName());
    col.setCaseSensitive(colRef.isCaseSensitive());
    if (col.getTableName() == null) {
      ArrayList<SelectItem> founds=select.searchByAlias(colRef.getColumnName(),colRef.isCaseSensitive());
      if (founds.size() == 1)       return null;
 else       if (founds.size() > 1)       throw new UnresolvedColumnException(col,founds.get(0).getAlias(),founds.get(1).getAlias());
    }
    return resolveColumn(col,dbColumns);
  }
}

Fixed version (ground truth):
/** 
 * Checks whether the given column reference corresponds to a selected item (column or an expression with an alias) or to an existing column.
 * @param colRef			The column reference which must be checked.
 * @param select			The SELECT clause of the ADQL query.
 * @param dbColumns			The list of all available {@link DBColumn}s.
 * @return 					The corresponding {@link DBColumn} if this reference is actually the name of a column, <i>null</i> otherwise.
 * @throws ParseException	An {@link UnresolvedColumnException} if the given column can't be resolvedor an  {@link UnresolvedTableException} if its table reference can't be resolved.
 * @see ClauseSelect#searchByAlias(String)
 * @see #resolveColumn(ADQLColumn,SearchColumnList,SearchColumnList)
 */
protected DBColumn checkColumnReference(final ColumnReference colRef,final ClauseSelect select,final SearchColumnList dbColumns) throws ParseException {
  if (colRef.isIndex()) {
    int index=colRef.getColumnIndex();
    if (index > 0 && index <= select.size()) {
      SelectItem item=select.get(index - 1);
      if (item.getOperand() instanceof ADQLColumn)       return ((ADQLColumn)item.getOperand()).getDBLink();
 else       return null;
    }
 else     throw new ParseException("String_Node_Str" + index + "String_Node_Str"+ select.size()+ "String_Node_Str");
  }
 else {
    ADQLColumn col=new ADQLColumn(colRef.getColumnName());
    col.setCaseSensitive(colRef.isCaseSensitive());
    if (col.getTableName() == null) {
      ArrayList<SelectItem> founds=select.searchByAlias(colRef.getColumnName(),colRef.isCaseSensitive());
      if (founds.size() == 1)       return null;
 else       if (founds.size() > 1)       throw new UnresolvedColumnException(col,founds.get(0).getAlias(),founds.get(1).getAlias());
    }
    return resolveColumn(col,dbColumns,null);
  }
}