public Builder requestPreProcessor(UnaryOperator<HttpRequest<Buffer>> requestPreProcessor) {
      this.requestPreProcessor =
          checkNotNull(requestPreProcessor, "Argument requestPreProcessor must be not null");
      return this;
    }
Defines operation to execute on each {@link HttpRequest} before it sent. Used to make setup
on request level.

<p>Example:

<pre>
var client = VertxFeign
    .builder()
    .vertx(vertx)
    .requestPreProcessor(req -&#62; req.ssl(true));
</pre>

@param requestPreProcessor operation to execute on each request
@return updated request
vertx/feign-vertx/src/main/java/feign/VertxFeign.java