private boolean isReactive(Type type) {
    if (!ParameterizedType.class.isAssignableFrom(type.getClass())) {
      return false;
    }
    ParameterizedType parameterizedType = (ParameterizedType) type;
    Class<?> raw = (Class<?>) parameterizedType.getRawType();
    return Publisher.class.isAssignableFrom(raw);
  }
Ensure that the type provided implements a Reactive Streams Publisher.

@param type to inspect.
@return true if the type implements the Reactive Streams Publisher specification.
reactive/src/main/java/feign/reactive/ReactiveDelegatingContract.java