NullDuration regex is incorrect

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Ory Network Project

No response

Describe the bug

The hydra sdk spec defines NullDuration with the following pattern: ^([0-9]+(ns|us|ms|s|m|h))*$.

The kratos and the "client" (combined) spec define it as ^[0-9]+(ns|us|ms|s|m|h)$ which causes values such as "2m0s" to fail validation.

I think that in both cases the regex should actually be ^([0-9]+(ns|us|ms|s|m|h))+$, depending on whether an empty string is valid or not.

Reproducing the bug

Discovered with a generated python+pydantic client. After changing authorization_code_grant_access_token_lifespan to "2m" (for testing purposes) hydra changed the value to "2m0s" which caused subsequent calls to the GET client endpoint to fail with a pydantic ValidationError.

Relevant log output

Relevant configuration

Version

Kratos 1.3.1 / Hydra 2.2.0

On which operating system are you observing this issue?

Linux

In which environment are you deploying?

Docker

Additional Context

No response

Locate the NullDuration pattern in the Hydra, Kratos, and combined client specs, then compare how the generated Python/Pydantic client validates values such as "2m0s". Done means the affected specs accept the intended duration format consistently, with the empty-string behavior decided and covered by validation tests.