code: @Nullable
    private String[] getReplacementCmd(String cmd) {
      if (mCommandAlias == null || !mCommandAlias.containsKey(cmd)) {
        return null;
      }
      return mCommandAlias.get(cmd);
    }
docs: Gets the replacement command for alias.
  
  @param cmd the name of the command
  @return replacement command if cmd is an alias