## [Calls](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-call/)

With rewrites, redirects, follow-ups and retries, your simple request may yield many requests and responses. OkHttp uses `Call` to model the task of satisfying your request through however many intermediate requests and responses are necessary. Typically this isn’t many! But it’s comforting to know that your code will continue to work if your URLs are redirected or if you failover to an alternate IP address.

    assertThat(manyValuesAccumulatorByAddAllPartitionedPairedStats.populationCovariance())
        .isWithin(ALLOWED_ERROR)
        .of(MANY_VALUES_SUM_OF_PRODUCTS_OF_DELTAS / MANY_VALUES_COUNT);
    // For datasets of many double values, we test many combinations of finite and non-finite
    // x-values:
    for (ManyValues values : ALL_MANY_VALUES) {
      PairedStatsAccumulator accumulator =

        .of(MANY_VALUES_MEAN);
    assertThat(manyValuesAccumulatorByAddAllStatsAccumulator.mean())
        .isWithin(ALLOWED_ERROR)
        .of(MANY_VALUES_MEAN);
    // For datasets of many double values created from an iterable, we test many combinations of
    // finite and non-finite values:
    for (ManyValues values : ALL_MANY_VALUES) {
      StatsAccumulator accumulator = new StatsAccumulator();

        value = "${spaces}";
        assertEquals("   ", ResourceUtil.resolve(value));

        // Test long property name
        System.setProperty("very.long.property.name.with.many.dots", "long");
        value = "${very.long.property.name.with.many.dots}";
        assertEquals("long", ResourceUtil.resolve(value));

        // Test multiple occurrences of same variable
        System.setProperty("repeat", "X");

 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

organization-specific certificate authority.

By default `HeldCertificate` instances expire after 24 hours. Use `duration()` to adjust.

By default server certificates need to identify which hostnames they're trusted for. You may add as
many as necessary with `addSubjectAlternativeName()`. This mechanism also supports a very limited
form of wildcards `*.example.com` where the `*` must be first and doesn't match nested subdomains.

        assertFalse(validator.determineValid("too many fields here * * * * * * *"));
        assertFalse(validator.determineValid("* * * *"));
    }

    public void test_isValid_basicInvalidCronExpression() {
        final ConstraintValidatorContext context = null;
        assertFalse(validator.isValid("invalid cron", context));
        assertFalse(validator.isValid("too many fields * * * * * * *", context));

   * non-nullable {@code cause}, as many users expect to find one.
   */
  public ExecutionError(@Nullable String message, @Nullable Error cause) {
    super(message, cause);
  }

  /**
   * Creates a new instance with {@code null} as its detail message and the given cause. Prefer to
   * provide a non-nullable {@code cause}, as many users expect to find one.
   */

   * non-nullable {@code cause}, as many users expect to find one.
   */
  public UncheckedExecutionException(@Nullable String message, @Nullable Throwable cause) {
    super(message, cause);
  }

  /**
   * Creates a new instance with {@code null} as its detail message and the given cause. Prefer to
   * provide a non-nullable {@code cause}, as many users expect to find one.
   */

- Don’t change public API lightly, avoid if possible, and include your reasoning in the PR if essential.  It causes pain for developers who use OkHttp and sometimes runtime errors.
- Favour a working external library if appropriate.  There are many examples of OkHttp libraries that can sit on top or hook in via existing APIs.
- Get working code on a personal branch with tests before you submit a PR.