Program: 121811
Project: 121811
Buggy source:
@Override protected String initExpression(DbMapComponent component,ExternalDbMapEntry dbMapEntry){
  String expression=dbMapEntry.getExpression();
  if (expression != null) {
    List<? extends IConnection> inputConnections=component.getIncomingConnections();
    ExternalDbMapData data=(ExternalDbMapData)component.getExternalData();
    if (inputConnections == null) {
      return expression;
    }
    for (    ExternalDbMapTable input : data.getInputTables()) {
      ExternalDbMapTable inputTable=input;
      IConnection connection=null;
      for (      IConnection iconn : inputConnections) {
        if (iconn.getName().equals(input.getTableName())) {
          connection=iconn;
          break;
        }
      }
      if (connection == null) {
        return expression;
      }
      INode source=connection.getSource();
      String schemaStr="String_Node_Str";
      String tableNameStr="String_Node_Str";
      if (source != null) {
        IElementParameter schema=source.getElementParameter("String_Node_Str");
        IElementParameter tableName=source.getElementParameter("String_Node_Str");
        if (schema != null && schema.getValue() != null) {
          schemaStr=TalendTextUtils.removeQuotes(schema.getValue().toString());
        }
        if (tableName != null && tableName.getValue() != null) {
          tableNameStr=TalendTextUtils.removeQuotes(tableName.getValue().toString());
        }
      }
      for (      ExternalDbMapEntry co : inputTable.getMetadataTableEntries()) {
        String columnLabel=co.getName();
        String[] patternSubs=getPattenSubs(schemaStr,tableNameStr,columnLabel);
        MapExpressionParser parser=new MapExpressionParser(patternSubs[0]);
        expression=parser.replaceLocation(expression,patternSubs[0],patternSubs[1]);
        if (inputTable.getAlias() != null && !"String_Node_Str".equals(inputTable.getAlias())) {
          patternSubs=getPattenSubs("String_Node_Str",inputTable.getAlias(),columnLabel);
          parser=new MapExpressionParser(patternSubs[0]);
          expression=parser.replaceLocation(expression,patternSubs[0],patternSubs[1]);
        }
      }
    }
  }
  List<IMetadataTable> metadataList=component.getMetadataList();
  if (metadataList != null) {
    for (    IMetadataTable table : metadataList) {
      String tableName=table.getLabel();
      for (      IMetadataColumn column : table.getListColumns()) {
        String columnLabel=column.getLabel();
        String[] patternSubs=getPattenSubs("String_Node_Str",tableName,columnLabel);
        MapExpressionParser parser=new MapExpressionParser(patternSubs[0]);
        expression=parser.replaceLocation(expression,patternSubs[0],patternSubs[1]);
      }
    }
  }
  return expression;
}

Fixed version (ground truth):
@Override protected String initExpression(DbMapComponent component,ExternalDbMapEntry dbMapEntry){
  String expression=super.initExpression(component,dbMapEntry);
  if (expression != null) {
    List<? extends IConnection> inputConnections=component.getIncomingConnections();
    ExternalDbMapData data=(ExternalDbMapData)component.getExternalData();
    if (inputConnections == null) {
      return expression;
    }
    for (    ExternalDbMapTable input : data.getInputTables()) {
      ExternalDbMapTable inputTable=input;
      IConnection connection=null;
      for (      IConnection iconn : inputConnections) {
        if (iconn.getName().equals(input.getTableName())) {
          connection=iconn;
          break;
        }
      }
      if (connection == null) {
        return expression;
      }
      INode source=connection.getSource();
      String schemaStr="String_Node_Str";
      String tableNameStr="String_Node_Str";
      if (source != null) {
        IElementParameter schema=source.getElementParameter("String_Node_Str");
        IElementParameter tableName=source.getElementParameter("String_Node_Str");
        if (schema != null && schema.getValue() != null) {
          schemaStr=TalendTextUtils.removeQuotes(schema.getValue().toString());
        }
        if (tableName != null && tableName.getValue() != null) {
          tableNameStr=TalendTextUtils.removeQuotes(tableName.getValue().toString());
        }
      }
      for (      IMetadataColumn co : connection.getMetadataTable().getListColumns()) {
        String columnLabel=co.getOriginalDbColumnName();
        String[] patternSubs=getPattenSubs(schemaStr,tableNameStr,columnLabel);
        MapExpressionParser parser=new MapExpressionParser(patternSubs[0]);
        expression=parser.replaceLocation(expression,patternSubs[0],patternSubs[1]);
        if (inputTable.getAlias() != null && !"String_Node_Str".equals(inputTable.getAlias())) {
          patternSubs=getPattenSubs("String_Node_Str",inputTable.getAlias(),columnLabel);
          parser=new MapExpressionParser(patternSubs[0]);
          expression=parser.replaceLocation(expression,patternSubs[0],patternSubs[1]);
        }
      }
    }
  }
  List<IMetadataTable> metadataList=component.getMetadataList();
  if (metadataList != null) {
    for (    IMetadataTable table : metadataList) {
      String tableName=table.getLabel();
      for (      IMetadataColumn column : table.getListColumns()) {
        String columnLabel=column.getOriginalDbColumnName();
        String[] patternSubs=getPattenSubs("String_Node_Str",tableName,columnLabel);
        MapExpressionParser parser=new MapExpressionParser(patternSubs[0]);
        expression=parser.replaceLocation(expression,patternSubs[0],patternSubs[1]);
      }
    }
  }
  return expression;
}