Result reporters have the ability to generate a summary through their
getSummary callback.
It is possible for other result reporters to have access to all summaries through the ITestSummaryListener interface, which allows them to use other reporters' results.
NOTE: Result reporters run in order of definition in the Tradefed XML configuration. So a reporter usually only has access to summaries of reporters running before itself. This is not a very common scenario, and is used in limited ways by core result reporters.