### Question:
ProfilesConf implements PluginConf { @Override public String getHandler(String profileName) { return getProfile(profileName).getHandler(); } private  ProfilesConf();   ProfilesConf(String internalProfilesFilename, String externalProfilesFilename); static ProfilesConf getInstance(); @Override Map<String, String> getOptionMappings(String profileName); @Override Map<String, String> getPlugins(String profileName); @Override String getProtocol(String profileName); @Override String getHandler(String profileName);  }### Answer:
@Test public void testGetHandler() { ProfilesConf profilesConf = getProfilesConf("testGetProtocol"); assertEquals("FooProtocolHandler.class", profilesConf.getHandler("with-handler")); assertNull(profilesConf.getHandler("foo")); }