assertEscaping(e, "%7F", '\u007f'); // del
    assertEscaping(e, "%C2%80", '\u0080'); // xx-00010,x-000000
    assertEscaping(e, "%DF%BF", '\u07ff'); // xx-11111,x-111111
    assertEscaping(e, "%E0%A0%80", '\u0800'); // xxx-0000,x-100000,x-00,0000
    assertEscaping(e, "%EF%BF%BF", '\uffff'); // xxx-1111,x-111111,x-11,1111
    assertUnicodeEscaping(e, "%F0%90%80%80", '\uD800', '\uDC00');

    assertEquals("remove(present) should return the associated value", v0(), getMap().remove(k0()));
    assertEquals(
        "remove(present) should decrease a map's size by one.", initialSize - 1, getMap().size());
    expectMissing(e0());
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)
  public void testRemovePresentConcurrentWithEntrySetIteration() {
    assertThrows(

  @CollectionSize.Require(absent = ZERO)
  public void testPut_unsupportedPresentExistingValue() {
    try {
      assertEquals("put(present, existingValue) should return present or throw", v0(), put(e0()));
    } catch (UnsupportedOperationException tolerated) {
    }
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)

                v3(),
                (oldV, newV) -> {
                  assertEquals(v0(), oldV);
                  assertEquals(v3(), newV);
                  return null;
                }));
    expectMissing(e0());
  }

  public void testMergeNullValue() {
    try {
      getMap()
          .merge(
              k0(),
              null,
              (oldV, newV) -> {

    }

    @Override
    public SampleElements<Multiset.Entry<E>> samples() {
      SampleElements<E> samples = gen.samples();
      return new SampleElements<>(
          Multisets.immutableEntry(samples.e0(), 3),
          Multisets.immutableEntry(samples.e1(), 4),
          Multisets.immutableEntry(samples.e2(), 1),
          Multisets.immutableEntry(samples.e3(), 5),
          Multisets.immutableEntry(samples.e4(), 2));

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemovePresent() {
    assertTrue(multimap().remove(k0(), v0()));

    assertFalse(multimap().containsEntry(k0(), v0()));
    expectMissing(e0());
    assertEquals(getNumElements() - 1, multimap().size());
    assertGet(k0(), ImmutableList.<V>of());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_KEYS})

                k0(),
                (k, v) -> {
                  assertEquals(k0(), k);
                  assertEquals(v0(), v);
                  return null;
                }));
    expectMissing(e0());
    expectMissingKeys(k0());
    assertEquals(getNumElements() - 1, getMap().size());
  }

  @MapFeature.Require({SUPPORTS_PUT, SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)

                k0(),
                (k, v) -> {
                  assertEquals(k0(), k);
                  assertEquals(v0(), v);
                  return null;
                }));
    expectMissing(e0());
    expectMissingKeys(k0());
    assertEquals(getNumElements() - 1, getMap().size());
  }

  @MapFeature.Require({SUPPORTS_PUT, SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemovePresent() {
    assertTrue(multimap().remove(k0(), v0()));

    assertFalse(multimap().containsEntry(k0(), v0()));
    expectMissing(e0());
    assertEquals(getNumElements() - 1, multimap().size());
    assertGet(k0(), ImmutableList.<V>of());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_KEYS})

    assertEscaping(e, "%7F", '\u007f'); // del
    assertEscaping(e, "%C2%80", '\u0080'); // xx-00010,x-000000
    assertEscaping(e, "%DF%BF", '\u07ff'); // xx-11111,x-111111
    assertEscaping(e, "%E0%A0%80", '\u0800'); // xxx-0000,x-100000,x-00,0000
    assertEscaping(e, "%EF%BF%BF", '\uffff'); // xxx-1111,x-111111,x-11,1111
    assertUnicodeEscaping(e, "%F0%90%80%80", '\uD800', '\uDC00');