default RestClientPreparation post(String path) {
        return path(HttpMethod.POST, path);
    }
Sets an {@link HttpMethod#POST} and the {@code path} and returns a fluent request builder.
<pre>{@code
RestClient restClient = RestClient.of("...");
CompletableFuture<ResponseEntity<Result>> response =
    restClient.post("/api/v1/customers")
              .contentJson(new Customer(...))
              .execute(Result.class);
}</pre>
core/src/main/java/com/linecorp/armeria/client/RestClient.java