return next;
            }
            horizon.addFirst(successors);
            ancestorStack.push(next);
          }
          // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
          if (!ancestorStack.isEmpty()) {
            return ancestorStack.pop();
          }
          return endOfData();
        }
      };
    }

    /**

@AndroidIncompatible // lots of failures, possibly some related to bad equals() implementations?
public class InvokableTest extends TestCase {
  // Historically Invokable inherited from java.lang.reflect.AccessibleObject. That's no longer the
  // case, but we do check that its API still has the same public methods. We exclude some methods
  // that were added in Java 9 and that people probably weren't calling via Invokable, namely

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;

    reverse(array, newFirstIndex, toIndex);
    reverse(array, fromIndex, toIndex);
  }

  /**
   * Returns an array containing each value of {@code collection}, converted to a {@code float}
   * value in the manner of {@link Number#floatValue}.
   *
   * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
   * Calling this method is as thread-safe as calling that method.
   *

        TimeUnit unit,
        Class<?> cls,
        Joiner joiner,
        Pattern pattern,
        UnsignedInteger ui,
        UnsignedLong ul,
        StringBuilder sb,
        Predicate<?> pred,
        Function<?, ?> func,
        Object obj) {
      delegate.foo(
          s, r, n, it, b, eq, e, in, c, ord, charset, unit, cls, joiner, pattern, ui, ul, sb, pred,
          func, obj);
    }

  public <T> void testRejectTypeVariable_withOwnerType() {
    // Neither has subclass
    assertHasTypeVariable(new From<Integer>().new To<String>().type());
    assertHasTypeVariable(new From<T>().new To<String>().type());
    assertHasTypeVariable(new From<Integer>().new To<T>().type());

    // Owner is subclassed

 *
 * @author Ben Yu
 */
@ElementTypesAreNonnullByDefault
final class Types {

  /** Class#toString without the "class " and "interface " prefixes */
  private static final Joiner COMMA_JOINER = Joiner.on(", ").useForNull("null");

  /** Returns the array type of {@code componentType}. */
  static Type newArrayType(Type componentType) {
    if (componentType instanceof WildcardType) {

import static com.google.common.truth.Truth.assertThat;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Ascii;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableList;
import com.google.common.io.BaseEncoding.DecodingException;
import java.io.IOException;
import java.io.InputStream;

  }

  @Generates
  <T> com.google.common.base.Optional<T> generateGoogleOptional(T value) {
    return com.google.common.base.Optional.of(value);
  }

  @Generates
  Joiner generateJoiner() {
    return Joiner.on(generateString());
  }

  @Generates
  Splitter generateSplitter() {
    return Splitter.on(generateString());
  }

  @Generates
  <T> Equivalence<T> generateEquivalence() {

import static org.junit.Assert.assertThrows;

import com.google.common.base.CharMatcher;
import com.google.common.base.Charsets;
import com.google.common.base.Equivalence;
import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.common.base.Splitter;
import com.google.common.base.Stopwatch;
import com.google.common.base.Ticker;
import com.google.common.collect.BiMap;