containers) when defining configurable parts of a plugin (tasks, extensions, domain objects).  The Provider API provides a consistent way to set conventions, wire related configuration together (extension <- domain object <- task) and avoid evaluation ordering problems.

The Gradle codebase has evolved over time and has a mixture of simple getter/setter methods, Provider API and things in between.  It can be hard to follow best practices because Gradle provided types are reused in unexpected ways...

        if (forwardCmp == null) {
          forwardCmp = (Comparator) Ordering.natural();
        }
        result = comparator = reverse(forwardCmp);
      }
      return result;
    }

    // If we inline this, we get a javac error.
    private static <T extends @Nullable Object> Ordering<T> reverse(Comparator<T> forward) {
      return Ordering.from(forward).reverse();
    }

    @Override

        if (forwardCmp == null) {
          forwardCmp = (Comparator) Ordering.natural();
        }
        result = comparator = reverse(forwardCmp);
      }
      return result;
    }

    // If we inline this, we get a javac error.
    private static <T extends @Nullable Object> Ordering<T> reverse(Comparator<T> forward) {
      return Ordering.from(forward).reverse();
    }

    @Override

   * support concurrent multimaps whose content may change while the method is running. The {@link
   * Multimap#asMap} view determines the ordering in which data is written to the stream.
   *
   * <p>The serialized output consists of the number of distinct keys, and then for each distinct
   * key: the key, the number of values for that key, and the key's values.
   */

  @Test
  public void edgeValueOrDefault_undirected_mismatch() {
    graph = ValueGraphBuilder.undirected().build();
    graph.putEdgeValue(1, 2, "A");
    // Check that edgeValueOrDefault() throws on each possible ordering of an ordered EndpointPair
    IllegalArgumentException e =
        assertThrows(
            IllegalArgumentException.class,
            () -> graph.edgeValueOrDefault(EndpointPair.ordered(1, 2), "default"));

import com.google.common.collect.Maps;
import com.google.common.collect.MultimapBuilder;
import com.google.common.collect.Multimaps;
import com.google.common.collect.Multiset;
import com.google.common.collect.Ordering;
import com.google.common.collect.SetMultimap;
import com.google.common.util.concurrent.Service.State;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.GuardedBy;

import com.google.common.collect.Maps;
import com.google.common.collect.MultimapBuilder;
import com.google.common.collect.Multimaps;
import com.google.common.collect.Multiset;
import com.google.common.collect.Ordering;
import com.google.common.collect.SetMultimap;
import com.google.common.util.concurrent.Service.State;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.GuardedBy;

  /**
   * Compares the specified object to this multimap for equality.
   *
   * <p>Two {@code SetMultimap} instances are equal if, for each key, they contain the same values.
   * Equality does not depend on the ordering of keys or values.
   *
   * <p>An empty {@code SetMultimap} is equal to any other empty {@code Multimap}, including an
   * empty {@code ListMultimap}.
   */
  @Override
  boolean equals(@Nullable Object obj);

  /**
   * Compares the specified object to this multimap for equality.
   *
   * <p>Two {@code SetMultimap} instances are equal if, for each key, they contain the same values.
   * Equality does not depend on the ordering of keys or values.
   *
   * <p>An empty {@code SetMultimap} is equal to any other empty {@code Multimap}, including an
   * empty {@code ListMultimap}.
   */
  @Override
  boolean equals(@Nullable Object obj);

import static java.math.RoundingMode.UNNECESSARY;
import static org.junit.Assert.assertThrows;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Ordering;
import com.google.common.math.Quantiles.ScaleAndIndexes;
import com.google.common.primitives.Doubles;
import com.google.common.primitives.Ints;
import com.google.common.primitives.Longs;