@Test
  void resolveTemplateWithMixedCollectionFormatsByQuery() {
    RequestTemplate template =
        new RequestTemplate()
            .method(HttpMethod.GET)
            .collectionFormat(CollectionFormat.EXPLODED)
            .uri("/api/collections")
            .query("keys", "{keys}") // default
            // collection
            // format
            .query("values[]", Collections.singletonList("{values[]}"), CollectionFormat.CSV);

    template =
        template.resolve(
            mapOf("keys", Arrays.asList("one", "two"), "values[]", Arrays.asList("1", "2")));

    assertThat(template.url())
        .isEqualToIgnoringCase("/api/collections?keys=one&keys=two&values%5B%5D=1%2C2");
  }
Avoid depending on guava solely for map literals.
core/src/test/java/feign/RequestTemplateTest.java