@JsonIgnore
    public Multimap<String, String> getHeaders() {
        return headers;
    }
@Test
    void testToAndFromJson() throws JsonProcessingException {
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders
                .getHeaders().put("nick1", "val1");
        httpHeaders
                .getHeaders().put("nick2", "val2");

        String json = om.writeValueAsString(httpHeaders);

        HttpHeaders additionalHttpHeaders2 = om.readValue(json, HttpHeaders.class);
        assertEquals(httpHeaders, additionalHttpHeaders2);
    }