### Question:
ConfigurationEntry { public boolean isStable() { return this.oldConf.isEmpty(); } ConfigurationEntry();  ConfigurationEntry(final LogId id, final Configuration conf, final Configuration oldConf); LogId getId(); void setId(final LogId id); Configuration getConf(); void setConf(final Configuration conf); Configuration getOldConf(); void setOldConf(final Configuration oldConf); boolean isStable(); boolean isEmpty(); Set<PeerId> listPeers(); boolean isValid(); Set<PeerId> listLearners(); boolean containsLearner(final PeerId learner); boolean contains(final PeerId peer); @Override String toString();  }### Answer:
@Test public void testIsStable() { ConfigurationEntry entry = TestUtils.getConfEntry("localhost:8081,localhost:8082,localhost:8083", "localhost:8080,localhost:8081,localhost:8082"); assertFalse(entry.isStable()); assertEquals(4, entry.listPeers().size()); assertTrue(entry.contains(new PeerId("localhost", 8080))); assertTrue(entry.contains(new PeerId("localhost", 8081))); assertTrue(entry.contains(new PeerId("localhost", 8082))); assertTrue(entry.contains(new PeerId("localhost", 8083))); }