FluentIterable<TimeUnit> unused = FluentIterable.from(TimeUnit.values()).append(SECONDS);
  }

  public void testFromArrayAndIteratorRemove() {
    FluentIterable<TimeUnit> units = FluentIterable.from(TimeUnit.values());
    assertThrows(UnsupportedOperationException.class, () -> removeIf(units, equalTo(SECONDS)));
  }

  public void testFrom() {
    assertEquals(
        ImmutableList.of(1, 2, 3, 4),

    assertThat(onlyPresent).containsExactly(2);
  }

  private static Optional<Integer> getSomeOptionalInt() {
    return Optional.of(1);
  }

  private static FluentIterable<? extends Number> getSomeNumbers() {
    return FluentIterable.from(ImmutableList.<Number>of());
  }

  /*
   * The following tests demonstrate the shortcomings of or() and test that the casting workaround

  public static <E> Iterable<E> unmodifiableIterable(ImmutableCollection<E> iterable) {
    return checkNotNull(iterable);
  }

  private static final class UnmodifiableIterable<T extends @Nullable Object>
      extends FluentIterable<T> {
    private final Iterable<? extends T> iterable;

    private UnmodifiableIterable(Iterable<? extends T> iterable) {
      this.iterable = iterable;
    }

    @Override

  public void testConstants_areUnique() {
    assertThat(getConstants()).containsNoDuplicates();
  }

  @J2ktIncompatible
  @GwtIncompatible // reflection
  private static FluentIterable<Field> getConstantFields() {
    return FluentIterable.from(asList(MediaType.class.getDeclaredFields()))
        .filter(
            field -> {
              int modifiers = field.getModifiers();
              return isPublic(modifiers)

   *
   * <p><b>Note:</b> if mutability is not required and the elements are non-null, use {@link
   * ImmutableList#copyOf(Iterable)} instead. (Or, change {@code elements} to be a {@link
   * FluentIterable} and call {@code elements.toList()}.)
   *
   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method. Use

import org.jspecify.annotations.Nullable;

/**
 * A comparator, with additional methods to support common operations. This is an "enriched" version
 * of {@code Comparator} for pre-Java-8 users, in the same sense that {@link FluentIterable} is an
 * enriched {@link Iterable} for pre-Java-8 users.
 *
 * <h3>Three types of methods</h3>
 *
 * Like other fluent types, there are three types of methods present: methods for <i>acquiring</i>,

    return FluentIterable.from(resources).filter(ClassInfo.class).toSet();
  }

  /**
   * Returns all top level classes loadable from the current class path. Note that "top-level-ness"
   * is determined heuristically by class name (see {@link ClassInfo#isTopLevel}).
   */
  public ImmutableSet<ClassInfo> getTopLevelClasses() {
    return FluentIterable.from(resources)
        .filter(ClassInfo.class)

import static java.util.Objects.requireNonNull;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ForwardingSet;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;