how to write query to get Documents in a particular product?

Well, it is returning array, use the following code to get pass the error

QuerySpec queryspec = new QuerySpec(WTDocumentMaster.class);
  queryspec.setAdvancedQueryEnabled(true); 
  int contIndex = queryspec.appendClassList(PDMLinkProduct.class,false);
  SearchCondition sc1 = new SearchCondition(WTDocumentMaster.class, "containerReference.key.id",PDMLinkProduct.class, wt.util.WTAttributeNameIfc.ID_NAME);
  queryspec.appendWhere(sc1, new int[] { 0, contIndex });
  queryspec.appendAnd();
  SearchCondition scSWPart = new SearchCondition(PDMLinkProduct.class ,"containerInfo.name",SearchCondition.EQUAL,"TestProduct1",true);
  queryspec.appendWhere(scSWPart,new int[] { contIndex });
  QueryResult queryResult = PersistenceHelper.manager.find(queryspec);
  System.out.println("Size :- " + queryResult.size());
  int size = queryResult.size();
  System.out.println("WTDocument query result size: " + size);


  while (queryResult.hasMoreElements()) {
  wt.fc.Persistable persisArray []= (Persistable[]) queryResult.nextElement();
  wt.doc.WTDocumentMaster doc=(WTDocumentMaster) persisArray[0];
  System.out.println(doc);
  }

Regards,

Bhushan