I have used the solution from this answer: Get list of JSON objects with Spring RestTemplate It works perfectly. It doing exactly what I need.
ProcessDefinition[] response = restTemplate.getForObject(url, ProcessDefinition[].class);
Is it enought:
return Arrays.asList(response);
or will be better this way:
return Arrays.asList(Optional.ofNullable(response).orElse(new ProcessDefinition[0]));
P.S. Sorry for starting the new topic, but my karma does not allow me to comment the answer.