private void MergeQueryDefinitions(Query newQueryDefinition)
{
// if current query definition is the one created by index searcher - replace; otherwise - merge
QueryDefinition = IsUsingDefaultQueryDefinition
? newQueryDefinition
: QueryHelper.MergeQueries(QueryDefinition, newQueryDefinition, BooleanClause.Occur.MUST, BooleanClause.Occur.MUST);
IsUsingDefaultQueryDefinition = false;
}