*
     * @param project {@link Project} or {@code null}.
     * @return the effective properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getEffectiveProperties(@Nullable Project project);

    /**
     * Returns the current maven version
     * @return the maven version, never {@code null}
     */
    @Nonnull
    Version getMavenVersion();

    int getDegreeOfConcurrency();

    @Override
    Set<E> createElementSet() {
      return Sets.filter(unfiltered.elementSet(), predicate);
    }

    @Override
    Iterator<E> elementIterator() {
      throw new AssertionError("should never be called");
    }

    @Override
    Set<Entry<E>> createEntrySet() {
      return Sets.filter(
          unfiltered.entrySet(),
          new Predicate<Entry<E>>() {
            @Override

   * <p>Note in particular that an equivalence wrapper is never equal to the object it wraps.
   *
   * <pre>{@code
   * equiv.wrap(obj).equals(obj) // always false
   * }</pre>
   *
   * @since 10.0
   */
  public static final class Wrapper<T extends @Nullable Object> implements Serializable {
    /*
     * Equivalence's type argument is always non-nullable: Equivalence<Number>, never

    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}

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

/**
 * A {@link BiMap} whose contents will never change, with many other important properties detailed
 * at {@link ImmutableCollection}.
 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)
@ElementTypesAreNonnullByDefault

              <!-- was only a workaround for Plexus Container, hopefully never used by anyone else -->
              <exclude>org.apache.maven.plugin.DefaultBuildPluginManager#setMojoExecutionListeners(java.util.List)</exclude>
              <!-- could have never been used due to usage of non-export class (CoreExportsProvider) -->

		if format == nil {
			continue
		}
		// NOTE: This code is specifically needed when migrating version
		// V1 to V2 to V3, in a scenario such as this we only need to handle
		// single sets since we never used to support multiple sets in releases
		// with V1 format version.
		if len(format.Erasure.Sets) > 1 {
			continue
		}
		if format.Erasure.This == "" {
			return true
		}
	}
	return false
}

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=

//
// A bucket root will never be compacted.
//
// Furthermore if a has more than dataScannerCompactAtChildren recursive children (uncompacted folders)
// the tree will be recursively scanned and the branches with the least number of objects will be
// compacted until the limit is reached.
//
// This ensures that any branch will never contain an unreasonable amount of other branches,

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

/**
 * A {@link Set} whose contents will never change, with many other important properties detailed at
 * {@link ImmutableCollection}.
 *
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)