private static <K, V> Map<K, V> mapOf(K k1, V v1, K k2, V v2, K k3, V v3) {
    Map<K, V> result = mapOf(k1, v1, k2, v2);
    result.put(k3, v3);
    return result;
  }
Avoid depending on guava solely for map literals.
core/src/test/java/feign/RequestTemplateTest.java