* @return This request for chaining, never {@code null}.
     * @see #setRemoteRepositories(List)
     */
    ProjectBuildingRequest setRepositoryMerging(RepositoryMerging mode);

    /**
     * Gets the merge mode used to combine repositories declared in the POM with the repositories specified in this
     * request
     *
     * @return The merge mode, never {@code null}.
     */

    if (tree instanceof BaseGraph) {
      checkArgument(((BaseGraph<?>) tree).isDirected(), "Undirected graphs can never be trees.");
    }
    if (tree instanceof Network) {
      checkArgument(((Network<?, ?>) tree).isDirected(), "Undirected networks can never be trees.");
    }
    return new Traverser<N>(tree) {
      @Override
      Traversal<N> newTraversal() {

   * convenient.
   *
   * <p>By default, a {@code Builder} will generate bimaps that iterate over entries in the order
   * they were inserted into the builder. For example, in the above example, {@code
   * WORD_TO_INT.entrySet()} is guaranteed to iterate over the entries in the order {@code "one"=1,
   * "two"=2, "three"=3}, and {@code keySet()} and {@code values()} respect the same order. If you

       * currentEntry above. After that, we never clear it.
       */
      return requireNonNull(currentEntry).getKey();
    }

    @Override
    public void remove() {
      checkRemove(canRemove);
      /*
       * requireNonNull is safe because canRemove is set to true only after we initialize
       * currentEntry (which we never subsequently clear).
       */

    throw new AssertionError("should never be called");
  }

  @Override
  public ImmutableCollection<V> values() {
    return (ImmutableCollection<V>) super.values();
  }

  @Override
  abstract ImmutableCollection<V> createValues();

  @Override
  final Iterator<V> valuesIterator() {
    throw new AssertionError("should never be called");
  }

  /**
   * {@inheritDoc}

     * in the former case, this method can never return zero, while in the latter, it will return
     * zero if all occurrences of the element were since removed from the multiset.
     *
     * @return the count of the element; never negative
     */
    int getCount();

    /**
     * {@inheritDoc}
     *

import java.util.stream.Collector;
import java.util.stream.Stream;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link ListMultimap} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * <p>See the Guava User Guide article on <a href=

     *
     * @param prefix The prefix of the plugin.
     * @return This request, never {@code null}.
     */
    PluginPrefixRequest setPrefix(String prefix);

    /**
     * Gets the list of group ids to scan for the plugin prefix.
     *
     * @return The list of group ids to scan for the plugin prefix, never {@code null}.
     */
    List<String> getPluginGroups();

    /**

import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link Multimap} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Warning:</b> avoid <i>direct</i> usage of {@link ImmutableMultimap} as a type (as with

     *
     * @return The identifiers of those profiles to activate, never {@code null}.
     */
    List<String> getActiveProfileIds();

    /**
     * Gets the identifiers of those profiles that should be deactivated by explicit demand.
     *
     * @return The identifiers of those profiles to deactivate, never {@code null}.
     */
    List<String> getInactiveProfileIds();

    /**