After upgrading to version 1, we got the following panic message:

Error: `panic: panicked at /usr/local/cargo/registry/src/index.crates.io-6f17d22bba15001f/backon-1.0.0/src/sleep.rs:33:9:
no sleeper has been configured, consider enabling features or provide a custom implementation` (on utils/src/tracers.rs:44)

IMO making it "silently" panicking (that is, there's no explicit API for picking the sleeper) is a pretty bad problem if you want to build a production-worthy library, and none of the examples make it clear that a sleeper impl must be configured.