code: public void setQueryCriteria(QueryDefinition querydef) {
      this.querydef = querydef;
      summary      = null;
      metrics      = null;
      facets       = null;
      warnings     = null;
      reports      = null;
      planEvents   = null;
      constraints  = null;
      events       = null;
      totalResults = -1;
      start        = -1;
      pageLength   = 0;
      snippetType  = null;
      qtext        = null;
      queryEvents  = null;
    }
docs: Sets the query definition used in the search.
  
  <p>Calling this method always deletes any cached search results.</p>
  
  @param querydef The new QueryDefinition