Background:

We're using Spring Boot 3.5.x with Micrometer 1.15.2, and would like to leverage the createdTimestamp feature introduced behind a feature flag on the Prometheus server.

On Prometheus server side this feature is only available if the Prometheus Protobuf Protocol is used.

In the Prometheus Java client, we noticed that the PrometheusProtobufWriterImpl currently only maps scrapeTimestampMillis from the DataPointSnapshot, but not the available createdTimestampMillis.

What we did:

We tested adding support for createdTimestampMillis in a fork of the latest release and confirmed that our counter metrics are now exposed with an initialized value of 0 as expected. This also builds on recent support added to Micrometer for this field (micrometer-metrics/micrometer#2625).

Proposal:

We propose updating PrometheusProtobufWriterImpl to also map and include createdTimestampMillis, similar to how scrapeTimestampMillis is currently handled. This would improve compatibility with Prometheus’ feature flag and help downstream libraries like Micrometer to fully support this newer functionality.

Would you be open to a PR for this? We're happy to contribute the necessary change if desired.

Thanks for your great work on this library!