### Question:
ConfigSourceMap extends AbstractMap<String, String> implements Map<String, String>, Serializable { public int size() { return delegate.getPropertyNames().size(); } ConfigSourceMap(final ConfigSource delegate); int size(); boolean isEmpty(); boolean containsKey(final Object key); String get(final Object key); Set<String> keySet(); Collection<String> values(); Set<Entry<String, String>> entrySet(); void forEach(final BiConsumer<? super String, ? super String> action);  }### Answer:
@Test public void testSize() { assertEquals(MANY_MAP.size(), new ConfigSourceMap(MANY_CONF_SRC).size()); assertEquals(ONE_MAP.size(), new ConfigSourceMap(ONE_CONF_SRC).size()); }