docs: public void update() throws ProponoException {
          if (partial) {
              throw new ProponoException("ERROR: attempt to update partial entry");
          }
          final EntityEnclosingMethod method = new PutMethod(getEditURI());
          addAuthentication(method);
          final StringWriter sw = new StringWriter();
          final int code = -1;
          try {
              Atom10Generator.serializeEntry(this, sw);
              method.setRequestEntity(new StringRequestEntity(sw.toString(), null, null));
              method.setRequestHeader("Content-type", "application/atom+xml; charset=utf-8");
              getHttpClient().executeMethod(method);
              final InputStream is = method.getResponseBodyAsStream();
              if (method.getStatusCode() != 200 && method.getStatusCode() != 201) {
                  throw new ProponoException("ERROR HTTP status=" + method.getStatusCode() + " : " + Utilities.streamToString(is));
              }
  
          } catch (final Exception e) {
              final String msg = "ERROR: updating entry, HTTP code: " + code;
              LOG.debug(msg, e);
              throw new ProponoException(msg, e);
          } finally {
              method.releaseConnection();
          }
      }