code: public void setCollection(String collection) throws PageException {
  	String[] collNames = ListUtil.toStringArrayTrim(ListUtil.listToArrayRemoveEmpty(collection, ','));
  	collections = new SearchCollection[collNames.length];
  	SearchEngine se = pageContext.getConfig().getSearchEngine(pageContext);
  	try {
  	    for (int i = 0; i < collections.length; i++) {
  		collections[i] = se.getCollectionByName(collNames[i]);
  	    }
  	}
  	catch (SearchException e) {
  	    collections = null;
  	    throw Caster.toPageException(e);
  	}
      }
docs: set the value collection The logical collection name that is the target of the search operation
  or an external collection with fully qualified path.
  
  @param collection value to set
  @throws PageException