code: public ClientVpnEndpoint withAuthenticationOptions(ClientVpnAuthentication... authenticationOptions) {
          if (this.authenticationOptions == null) {
              setAuthenticationOptions(new com.amazonaws.internal.SdkInternalList<ClientVpnAuthentication>(authenticationOptions.length));
          }
          for (ClientVpnAuthentication ele : authenticationOptions) {
              this.authenticationOptions.add(ele);
          }
          return this;
      }
docs: <p>
  Information about the authentication method used by the Client VPN endpoint.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setAuthenticationOptions(java.util.Collection)} or
  {@link #withAuthenticationOptions(java.util.Collection)} if you want to override the existing values.
  </p>
  
  @param authenticationOptions
  Information about the authentication method used by the Client VPN endpoint.
  @return Returns a reference to this object so that method calls can be chained together.