code: public Object executeIndexQuery(OIndex<?> index, INDEX_OPERATION_TYPE iOperationType, final List<Object> keyParams, final int fetchLimit) {
      return null;
    }
docs: Performs index query to calculate result of execution of given operator.
  <p/>
  Query that should be executed can be presented like: [[property0 = keyParam0] and [property1 = keyParam1] and] propertyN
  operator keyParamN.
  <p/>
  It is supped that index which passed in as parameter is used to index properties listed above and responsibility of given
  method execute query using given parameters.
  <p/>
  Multiple parameters are passed in to implement composite indexes support.
  
  @param index
  Instance of index that will be used to calculate result of operator execution.
  @param iOperationType TODO
  @param keyParams
  Parameters of query is used to calculate query result.
  @param fetchLimit
  Maximum amount of items to be fetched, corresponds to LIMIT operator in SQL query.
  @return Result of execution of given operator or {@code null} if given index can not be used to calculate operator result.