`OkHttpClient` has 26 accessors like `interceptors()` and `writeTimeoutMillis()` that were non-final
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

              <extraJvmArgs>-Dgwt.watchFileChanges=false</extraJvmArgs>
            </configuration>
          </execution>
          <!--
            GWT issues some scary warnings while running tests, but I believe they are harmless.
            Let's take the warnings for one module, c.g.c.base.testModule, as an example:

              [INFO] Validating units:

and then take a look at the
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These are issues that we believe are particularly well suited for outside
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decide to start on an issue, leave a comment so that other people know that

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    3.2. Modifications.

    The Modifications that You create or to which You contribute are
    governed by the terms of this License. You represent that You
    believe Your Modifications are Your original creation(s) and/or You
    have sufficient rights to grant the rights conveyed by this License.

    3.3. Required Notices.

      requireNonNull(impl);
      requireNonNull(other.impl);
      /*
       * For discussion of requireNonNull, see the comment on the field.
       *
       * (And I don't believe there's any situation in which we call x.combine(y) when x is a plain
       * ImmutableSet.Builder but y is an ImmutableSortedSet.Builder (or vice versa). Certainly