@Test
public void testMerge() throws IOException {

  ReportEvent e1 = new ReportEvent("test");
  e1.setLongMetric("another", 12345);
  long attrs = e.getNumMetrics();
  System.out.println("- before merge, " + attrs + " attributes");
  Writer out = new OutputStreamWriter(System.out);
  e.toJson(out);
  out.flush();
  System.out.println("- after merge, " + attrs + " + 1  attributes");
  e.merge(e1);
  e.toJson(out);
  out.flush();
  assertEquals(attrs + 1, e.getNumMetrics());
}