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(

   * Collector} will be compared to the expected value using the specified {@code equivalence}.
   */
  public static <T extends @Nullable Object, A extends @Nullable Object, R extends @Nullable Object>
      CollectorTester<T, A, R> of(
          Collector<T, A, R> collector, BiPredicate<? super R, ? super R> equivalence) {

import com.google.common.collect.testing.MapTestSuiteBuilder;
import com.google.common.collect.testing.TestEnumMapGenerator;
import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.testing.CollectorTester;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.stream.Collector;
import java.util.stream.Stream;
import junit.framework.Test;
import junit.framework.TestCase;

    }

    SerializableTester.reserializeAndAssert(test.keySet());

    SerializableTester.reserializeAndAssert(nonEmptyRangeMap);
  }

  // TODO(b/172823566): Use mainline testToImmutableRangeMap once CollectorTester is usable to java7
  public void testToImmutableRangeMap() {
    Range<Integer> rangeOne = Range.closedOpen(1, 5);
    Range<Integer> rangeTwo = Range.openClosed(6, 7);