vendor/league/oauth2-server-bundle/src/DependencyInjection/Configuration.php

->scalarNode('access_token_ttl')
    ->info("How long the issued access token should be valid for.\nThe value should be a valid interval: http://php.net/manual/en/dateinterval.construct.php#refsect1-dateinterval.construct-parameters")
    ->cannotBeEmpty()
    ->defaultValue('PT1H')
->end()
->scalarNode('refresh_token_ttl')
    ->info("How long the issued refresh token should be valid for.\nThe value should be a valid interval: http://php.net/manual/en/dateinterval.construct.php#refsect1-dateinterval.construct-parameters")
    ->cannotBeEmpty()
    ->defaultValue('P1M')