Supply lazy TemplateEngine, HttpClientFactory, and DefaultHttpClient.

[kyle-winkelman]

Draft for issue in which ExtensionFactories are supplied a null TemplateEngine, HttpClientFactory, and DefaultHttpClient from Extensions.

References

• closes Extensions always supplies a null TemplateEngine to ExtensionFactory #2562

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[tomakehurst]

This sort of thing is a shortcoming of not having full DI (which I briefly tried by decided against the added complexity).

The approach we're intending to promote to solve this is the Lazy class e.g. https://github.com/wiremock/wiremock/blob/master/src/main/java/org/wiremock/webhooks/Webhooks.java#L44

[kyle-winkelman]

What do you think of supplying lazy implementations as the PR currently reflects?

Do you know much about backwards compatibility? Because I contemplated turning TemplateEngine into an interface to make it easier to extend, but was unsure if that would maintain compatibility.

[tomakehurst]

Hmmmm...I hadn't thought of doing this way but I like it, I think...

[kyle-winkelman]

Haha I have a similar sentiment. I don't love this approach, but I can't think of a better way. Maybe explicitly creating classes named LazyTemplateEngine, LazyHttpClientFactory, and LazyHttpClient would help make it more clear?

Alternatively, we extensively document in Extending WireMock via custom code the limitations of using these methods.

[tomakehurst]

Yeah, I think creating top-level classes in the way you described would clarify things a bit.

How about we do that, then I'll merge it?

[kyle-winkelman]

Done!