CollectorTester<T, A, R> of(
          Collector<T, A, R> collector, BiPredicate<? super R, ? super R> equivalence) {
    return new CollectorTester<>(collector, equivalence);
  }

  private final Collector<T, A, R> collector;
  private final BiPredicate<? super R, ? super R> equivalence;

  private CollectorTester(

import com.google.common.collect.testing.google.TestStringListMultimapGenerator;
import com.google.common.collect.testing.google.UnmodifiableCollectionTests;
import com.google.common.primitives.Chars;
import com.google.common.testing.CollectorTester;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.NullPointerTester;
import com.google.common.testing.SerializableTester;
import java.util.Arrays;
import java.util.Collection;

    assertMapEquals(copy, "one", 1, "two", 2, "three", 3);
    assertSame(copy, ImmutableMap.copyOf(copy));
  }

  // TODO(b/172823566): Use mainline testToImmutableMap once CollectorTester is usable to java7.
  public void testToImmutableMap_java7_combine() {
    ImmutableMap.Builder<String, Integer> zis =
        ImmutableMap.<String, Integer>builder().put("one", 1);