protected Object[] extractNextValues(Iterator<?>[] iterators, List<DataProviderInfo> providerInfos) {
      Assert.that(iterators.length == providerInfos.size());
      Object[] result = new Object[iterators.length];
      for (int i = 0; i < iterators.length; i++) {
        try {
          result[i] = iterators[i].next();
        } catch (Throwable t) {
          supervisor.error(context.getErrorInfoCollector(), new ErrorInfo(providerInfos.get(i).getDataProviderMethod(), t, getErrorContext()));
          return null;
        }
      }
      return result;
    }
Returns how many data providers are processed by this data provider multiplier.

@return how many data providers are processed by this data provider multiplier
spock-core/src/main/java/org/spockframework/runtime/DataIteratorFactory.java