Make ApiClient in retrofit2 be able to use own OkHttpClient

Created by: tgerth

Description

If I want to set a customized okHttpClient to the adapterBuilder like this:

val apiClient = ApiClient()
apiClient.adapterBuilder
      .baseUrl(baseUrl)
      .client(customizedOkHttpClient)

the client gets overwritten by this:

public <S> S createService(Class<S> serviceClass) {
        return this.adapterBuilder.client(this.okBuilder.build()).build().create(serviceClass);
    }

and unfortunately this method:

public void configureFromOkclient(OkHttpClient okClient) {
        this.okBuilder = okClient.newBuilder();
        this.addAuthsToOkBuilder(this.okBuilder);
    }

is of no use to me because the okBuilder would just get the clients fields but I need/want to have the client itself respectively its instance. So I added a boolean field "okBuilderUsed" which checks if the okBuilder is used and if it's used then createService will return its client and if not then createService will just return the adapterBuilder:

public <S> S createService(Class<S> serviceClass) {
        return this.okBuilderUsed ? this.adapterBuilder.client(this.okBuilder.build()).build().create(serviceClass) : this.adapterBuilder.build().create(serviceClass);
    }

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