feat: [OpenAPI] Customize apache request object before invocation

[newtork]

Allows for runtime customization of request builder object before the ApiClient invocation.

Related:

• feat: [DevOps] Update sap-rpt specification ai-sdk-java#792
• https://github.com/SAP/ai-sdk-java-backlog/issues/379

Example:

  static RptClient forDestination(@Nonnull final Destination destination) {
    final var apiClient = ApiClient.create(destination)
        .withObjectMapper(getDefaultObjectMapper())
+       .withRequestCustomizer(request -> {
+         if(request.getPath().contains("/predict")) {
+           return request.addHeader("Accept-Encoding", "gzip");
+         }
+         return request;
+       });
    return new RptClient(new DefaultApi(apiClient));
  }

New methods:

+ ApiClient#withRequestCustomizer( UnaryOperator<ClassicRequestBuilder> )

[Jonas-Isr]

I like this! It looks pretty cool and should give us a clean solution to the GZIP problem.

Only one minor comment. Also would be interested in what the others think.

[rpanackal]

I tried different approaches that is more focused at modifying BaseApi class to achieve the same. But its either breaking, requires modifications to generated code or a lot of new public.

So, I think this is a great way to do this.

[newtork]

An alternative approach (with a less generic approach) is being discussed here:
#1130

[newtork]

Looks like we're preferring #1130 over this