There are, however, times when we cannot maintain complete compatibility.
If code depends on buggy (including insecure) behavior,
then fixing the bug will break that code.
New features can also have similar impacts:
enabling the HTTP/2 use by the HTTP client broke programs
connecting to servers with buggy HTTP/2 implementations.
These kinds of changes are unavoidable and

			// This is wrong and leads to an output file that mangles the
			// atime and ctime fields, which are often left unused.
			//
			// In order to continue reading tar files created by former, buggy
			// versions of Go, we skeptically parse the atime and ctime fields.
			// If we are unable to parse them and the prefix field looks like
			// an ASCII string, then we fallback on the pre-Go1.8 behavior

    }

    assertMoreInvariants(map);
  }

  @SuppressWarnings("CollectionIncompatibleType")
  private void assertEntrySetNotContainsString(Set<Entry<K, V>> entrySet) {
    // Very unlikely that a buggy collection would ever return true. It might accidentally throw.
    assertFalse(entrySet.contains("foo"));
  }

  /**
   * Override this to check invariants which should hold true for a particular implementation, but

    }

    assertMoreInvariants(map);
  }

  @SuppressWarnings("CollectionIncompatibleType")
  private void assertEntrySetNotContainsString(Set<Entry<K, V>> entrySet) {
    // Very unlikely that a buggy collection would ever return true. It might accidentally throw.
    assertFalse(entrySet.contains("foo"));
  }

  /**
   * Override this to check invariants which should hold true for a particular implementation, but

    sort(list, c);
    assertThat(list).containsExactly(8, 6, 7, 5, 3, 0, 9).inOrder();
    reserializeAndAssert(c);
  }

  @SuppressWarnings("DistinctVarargsChecker") // test of buggy call
  public void testExplicit_withDuplicates() {
    assertThrows(IllegalArgumentException.class, () -> Ordering.explicit(1, 2, 3, 4, 2));
  }

  // A more limited test than the one that follows, but this one uses the

    sort(list, c);
    assertThat(list).containsExactly(8, 6, 7, 5, 3, 0, 9).inOrder();
    reserializeAndAssert(c);
  }

  @SuppressWarnings("DistinctVarargsChecker") // test of buggy call
  public void testExplicit_withDuplicates() {
    assertThrows(IllegalArgumentException.class, () -> Ordering.explicit(1, 2, 3, 4, 2));
  }

  // A more limited test than the one that follows, but this one uses the

   *
   * @throws IllegalArgumentException if {@code x <= 0}
   * @since 20.0
   */
  public static long floorPowerOfTwo(long x) {
    checkPositive("x", x);

    // Long.highestOneBit was buggy on GWT.  We've fixed it, but I'm not certain when the fix will
    // be released.
    return 1L << ((Long.SIZE - 1) - Long.numberOfLeadingZeros(x));
  }

  /**

	}, {
		file: "testdata/issue11169.tar",
		err:  ErrHeader,
	}, {
		file: "testdata/issue12435.tar",
		err:  ErrHeader,
	}, {
		// Ensure that we can read back the original Header as written with
		// a buggy pre-Go1.8 tar.Writer.
		file: "testdata/invalid-go17.tar",
		headers: []*Header{{
			Name:     "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/foo",
			Uid:      010000000,