code: public static void setAccountSid(final String accountSid) {
          if (accountSid == null) {
              throw new AuthenticationException("AccountSid can not be null");
          }
  
          if (!accountSid.equals(Twilio.accountSid)) {
              Twilio.invalidate();
          }
  
          Twilio.accountSid = accountSid;
      }
docs: Set the account sid.
  
  @param accountSid account sid to use
  @throws AuthenticationException if account sid is null