code: public String convert(String input, String type) {
          // set necessary header: request per form
          HttpHeaders headers = new HttpHeaders();
          headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
  
          // pack the latex string as the parameter q (q for query ;) )
          MultiValueMap<String, String> map = new LinkedMultiValueMap<>();
          map.add("q", input);
          if (!type.isEmpty()) {
              map.add("type", type);
          }
  
          HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers);
          try {
              String rep = new RestTemplate().postForObject(mathoidConfig.getUrl(), request, String.class);
              logger.info(rep);
              return rep;
          } catch (HttpClientErrorException e) {
              logger.error(e.getResponseBodyAsString());
              throw e;
          }
      }
docs: Request against Mathoid to receive an enriched MathML.
  Input format can be chosen.
  
  @param input LaTeX formula to be converted
  @param type  input format
  @return Enrichted MathML String from mathoid