code: public Map<String, String> retrieveParameters(ModeledAuthenticatedUser user,
              String identifier) {
  
          Map<String, String> parameterMap = new HashMap<String, String>();
  
          // Determine whether we have permission to read parameters
          boolean canRetrieveParameters;
          try {
              canRetrieveParameters = hasObjectPermission(user, identifier,
                      ObjectPermission.Type.UPDATE);
          }
  
          // Provide empty (but mutable) map if unable to check permissions
          catch (GuacamoleException e) {
              return parameterMap;
          }
  
          // Populate parameter map if we have permission to do so
          if (canRetrieveParameters) {
              for (ConnectionParameterModel parameter : parameterMapper.select(identifier))
                  parameterMap.put(parameter.getName(), parameter.getValue());
          }
  
          return parameterMap;
  
      }
docs: Retrieves all parameters visible to the given user and associated with
  the connection having the given identifier. If the given user has no
  access to such parameters, or no such connection exists, the returned
  map will be empty.
  
  @param user
  The user retrieving connection parameters.
  
  @param identifier
  The identifier of the connection whose parameters are being
  retrieved.
  
  @return
  A new map of all parameter name/value pairs that the given user has
  access to.