code: public static Map.Entry<String, Map<String, ?>> gsmCallCommand(
              String phoneNumber, GsmCallActions gsmCallActions) {
          String[] parameters = new String[] {"phoneNumber", "action"};
          Object[] values = new Object[]{phoneNumber, gsmCallActions.name().toLowerCase()};
          return new AbstractMap.SimpleEntry<>(GSM_CALL, prepareArguments(parameters, values));
      }
docs: This method forms a {@link Map} of parameters for the element
  value replacement. It is used against input elements
  
  @param phoneNumber The phone number of message sender
  @param gsmCallActions One of available GSM call actions
  
  @return a key-value pair. The key is the command name. The value is a {@link Map} command arguments.