Cargo Features

mongodb-h2co3 has no features set by default.

mongodb-h2co3 = { version = "0.3.11", features = ["ssl", "lint"] }
ssl = openssl
lint = clippy

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

clippy lint?
openssl ssl?