* static final} constants.
 *
 * {@snippet :
 * // Bad! Do not do this!
 * Joiner joiner = Joiner.on(',');
 * joiner.skipNulls(); // does nothing!
 * return joiner.join("wrong", null, "wrong");
 * }
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/StringsExplained#joiner">{@code Joiner}</a>.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */

in OkHttp 3.x and are final in 4.x. These were made non-final for use with mocking frameworks like
[Mockito][mockito]. We believe subtyping `OkHttpClient` is the wrong way to test with OkHttp. If
you must, mock `Call.Factory` which is the interface that `OkHttpClient` implements.

#### Internal API changes

    /*
     * Since we use AtomicReferenceFieldUpdaterAtomicHelper by default, we'll "obviously" use it
     * even when Unsafe isn't available. But it's nice to have a check here to make sure that
     * nothing somehow goes wrong as the JDK restricts access to Unsafe.
     */
    checkHelperVersion(NO_UNSAFE, "AtomicReferenceFieldUpdaterAtomicHelper");
    /*
     * SynchronizedHelper is meant for Android, but our best way to test it is under the JVM.

        Smb2CreateResponse resp = new Smb2CreateResponse(config, "bad");

        byte[] header = buildSmb2Header();
        byte[] body = new byte[2 + 2 + 4];
        // Wrong structure size (e.g., 0)
        SMBUtil.writeInt2(0, body, 0);
        // The rest of the fields are irrelevant since it should fail early
        byte[] packet = buildPacket(header, body, null, null);

        @Test
        @DisplayName("Should throw exception for invalid structure size")
        void testInvalidStructureSize() {
            byte[] buffer = new byte[64];
            SMBUtil.writeInt2(16, buffer, 0); // Wrong structure size (should be 17)

            assertThrows(SMBProtocolDecodingException.class, () -> {
                response.readBytesWireFormat(buffer, 0);
            }, "Expected structureSize = 17");
        }

        int headerStart = 0;
        buildHeader(buf, headerStart, NtStatus.NT_STATUS_SUCCESS, 0x0001, 0x0L);

        int bodyStart = headerStart + Smb2Constants.SMB2_HEADER_LENGTH;
        // Wrong structure size (should be 9)
        SMBUtil.writeInt2(8, buf, bodyStart);
        SMBUtil.writeInt2(0, buf, bodyStart + 2);
        SMBUtil.writeInt2(Smb2Constants.SMB2_HEADER_LENGTH + 8, buf, bodyStart + 4);

    // unordered endpoints not OK for directed graph (undefined behavior)
    assertThat(edges).doesNotContain(EndpointPair.unordered(N1, N2));

    assertThat(edges).doesNotContain(EndpointPair.ordered(N2, N1)); // wrong order
    assertThat(edges).doesNotContain(EndpointPair.ordered(N2, N2)); // edge not present
    assertThat(edges).doesNotContain(EndpointPair.ordered(N3, N4)); // nodes not in graph
  }

   * transitionService in the wrong order due to a race. Due to the fact that it is a race this test
   * isn't guaranteed to expose the issue, but it is at least likely to become flaky if the race
   * sneaks back in, and in this case flaky means something is definitely wrong.
   *
   * <p>Before the bug was fixed this test would fail at least 30% of the time.
   */

 * static final} constants.
 *
 * {@snippet :
 * // Bad! Do not do this!
 * Joiner joiner = Joiner.on(',');
 * joiner.skipNulls(); // does nothing!
 * return joiner.join("wrong", null, "wrong");
 * }
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/StringsExplained#joiner">{@code Joiner}</a>.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */

			t.Errorf("Test %d: should fail but it passed", i)
		}
		if err == nil {
			if content := writer.Bytes(); !bytes.Equal(content, data[test.offset:test.offset+test.length]) {
				t.Errorf("Test %d: read returns wrong file content.", i)
			}
		}

		for i, r := range bitrotReaders {
			if r == nil {
				disks[i] = OfflineDisk
			}
		}
		if err == nil && !test.shouldFail {