public static Properties copyProperties(Properties properties) {
        final Properties copyProperties = new Properties();
        // guard against modification/removal of keys in the given properties (MNG-5670, MNG-6053, MNG-6105)
        synchronized (properties) {
            copyProperties.putAll(properties);
        }
        return copyProperties;
    }

  }

  public void testFinalizeClassHasNoNestedClasses() throws Exception {
    // Ensure that the Finalizer class has no nested classes.
    // See https://code.google.com/p/guava-libraries/issues/detail?id=1505
    assertEquals(Collections.emptyList(), Arrays.asList(Finalizer.class.getDeclaredClasses()));
  }

  }

  public void testFinalizeClassHasNoNestedClasses() throws Exception {
    // Ensure that the Finalizer class has no nested classes.
    // See https://code.google.com/p/guava-libraries/issues/detail?id=1505
    assertEquals(Collections.emptyList(), Arrays.asList(Finalizer.class.getDeclaredClasses()));
  }

### [Fast Fallback](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-ok-http-client/-builder/fast-fallback/)

Since version 5.0, `OkHttpClient` supports fast fallback, which is our implementation of Happy Eyeballs [RFC 6555](https://datatracker.ietf.org/doc/html/rfc6555).

With fast fallback, OkHttp attempts to connect to multiple web servers concurrently. It keeps whichever route connects first and cancels all of the others. Its rules are:

33E5          ; mapped                 ; 0036 65E5     # 1.1  IDEOGRAPHIC TELEGRAPH SYMBOL FOR DAY SIX
33E6          ; mapped                 ; 0037 65E5     # 1.1  IDEOGRAPHIC TELEGRAPH SYMBOL FOR DAY SEVEN
33E7          ; mapped                 ; 0038 65E5     # 1.1  IDEOGRAPHIC TELEGRAPH SYMBOL FOR DAY EIGHT

    return level3


@router4_override.get(
    "/override5",
    tags=["path5a", "path5b"],
    responses={
        405: {"description": "Client error level 5"},
        505: {"description": "Server error level 5"},
    },
    deprecated=True,
    callbacks=callback_router5.routes,
    dependencies=[Depends(dep5)],
    response_class=ResponseLevel5,
)

            39387, 35516, 26552, 39464, 1465, 2594, 33491, 2866, 6055, 31388, 34837, 39654, 29344,
            36746, 37799, 36447, 59016, 54176, 25810, 26326, 8596, 34690, 57361, 23167, 27762,
            32806, 25769, 36978, 1263, 27278, 39612, 5125, 65105, 32697, 44413, 6100, 39059, 55136,
            33828, 29835, 6079, 34631, 49480, 45806, 39243, 8239, 35763, 27609, 27859, 22821, 52244,

     * concurrently, returning once any connection connects successfully.
     *
     * This implements Happy Eyeballs ([RFC 6555][rfc_6555]), balancing connect latency vs.
     * wasted resources.
     *
     * Defaults to enabled, call with [fastFallback] = false to revert to 4.x behaviour.
     *
     * [rfc_6555]: https://datatracker.ietf.org/doc/html/rfc6555
     */
    fun fastFallback(fastFallback: Boolean) =
      apply {

  // 61,440 [chars 0x0800 to 0xFFFF, minus surrogates]
  private static final long THREE_BYTE_ROUNDTRIPPABLE_CHARACTERS =
      0xFFFF - 0x0800 + 1 - THREE_BYTE_SURROGATES;

  // 2,650,112
  private static final long EXPECTED_THREE_BYTE_ROUNDTRIPPABLE_COUNT =
      // All one byte characters
      (long) Math.pow(EXPECTED_ONE_BYTE_ROUNDTRIPPABLE_COUNT, 3)
          +

    X489,
    X490,
    X491,
    X492,
    X493,
    X494,
    X495,
    X496,
    X497,
    X498,
    X499,
    X500,
    X501,
    X502,
    X503,
    X504,
    X505,
    X506,
    X507,
    X508,
    X509,
    X510,
    X511,
    X512,
    X513,
    X514,
    X515,
    X516,
    X517,
    X518,
    X519,
    X520,
    X521,