code: public <T extends Aggregator<?>> T getIterationAggregator(String name) {
  		return this.runtimeContext.<T>getIterationAggregator(name);
  	}
docs: Gets the iteration aggregator registered under the given name. The iteration aggregator is combines
  all aggregates globally once per superstep and makes them available in the next superstep.
  
  @param name The name of the aggregator.
  @return The aggregator registered under this name, or null, if no aggregator was registered.