Merge default request config with local customizations [SPR-12583]

[spring-projects-issues]

Stéphane Nicoll opened SPR-12583 and commented

Before #17144, only the local customizations on the factory were available to each request and the defaults of the client were always ignored.

If the factory is defined with HttpClient, its default settings are taken into account as long as no local customizations are made. Therefore, all customizations should be set in the created client.

We can do better as from HttpComponents 4.4 since the default config of the HttpClient can be accessed. In that case we can retrieve that config and merge it with our local customizations instead of overriding everything else.

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Issue Links:

• Configured RequestConfig in HttpClient gets overwritten by default [SPR-12540] #17144 Configured RequestConfig in HttpClient gets overwritten by default
• HttpComponentsClientHttpRequestFactory should not depend on CloseableHttpClient [SPR-12826] #17423 HttpComponentsClientHttpRequestFactory should not depend on CloseableHttpClient

Referenced from: commits bce145c