public boolean addMetricCollector(final IGangliaMetricsCollector c){
  if (c == null)   throw new IllegalArgumentException();
  return metricCollectors.add(c);
}

public boolean addMetricCollector ( final IGangliaMetricsCollector c ) { if ( c == null ) throw new IllegalArgumentException ( ) ; return metricCollectors . add ( c ) ; }
register a metrics collector .
