code: public void signIn(Map<String, Object> formParams) throws AuthenticationApiException {
          Headers.Builder headerBuilder = new Headers.Builder();
          headerBuilder.add("Accept", "*/*");
          headerBuilder.add("Content-Type", "application/x-www-form-urlencoded");
  
          Request request = new Request.Builder()
                  .url(client.getBasePath() + "/sign-in")
                  .headers(headerBuilder.build())
                  .post(client.buildRequestBodyFormEncoding(formParams))
                  .build();
          try {
              this.client.getHttpClient().newCall(request).execute();
          } catch (IOException e) {
              throw new AuthenticationApiException("Authorization error", e);
          }
      }
docs: Perform form-based authentication.
  Perform form-based authentication by submitting an agent&#39;s username and password.
  
  @param formParams The form parameters, can be created via static methods
  @throws AuthenticationApiException if the call is unsuccessful.