### Question:
ErrorProneFlags implements Serializable { public static ErrorProneFlags empty() { return new ErrorProneFlags(ImmutableMap.of()); } private  ErrorProneFlags(ImmutableMap<String, String> flagsMap); static ErrorProneFlags empty(); static ErrorProneFlags fromMap(Map<String, String> flagsMap); ImmutableMap<String, String> getFlagsMap(); Optional<String> get(String key); Optional<Boolean> getBoolean(String key); Optional<T> getEnum(String key, Class<T> clazz); Optional<ImmutableSet<T>> getEnumSet(String key, Class<T> clazz); Optional<Integer> getInteger(String key); Optional<List<String>> getList(String key); Optional<Set<String>> getSet(String key); boolean isEmpty(); @CheckReturnValue ErrorProneFlags plus(ErrorProneFlags other); static Builder builder(); static final String PREFIX; }### Answer:
@Test public void empty() { ErrorProneFlags emptyFlags = ErrorProneFlags.empty(); assertThat(emptyFlags.isEmpty()).isTrue(); assertThat(emptyFlags.getFlagsMap().isEmpty()).isTrue(); ErrorProneFlags nonEmptyFlags = ErrorProneFlags.fromMap(ImmutableMap.of("a", "b")); assertThat(nonEmptyFlags.isEmpty()).isFalse(); assertThat(nonEmptyFlags.getFlagsMap().isEmpty()).isFalse(); }