876ffa4674
Fix file names of flat_map_identity test This patch fixes the file names of the `flat_map_identity` test. Previously, their names were started with `unnecessary_flat_map` even though the lint rule name is `flat_map_identity`. This inconsistency happened probably because the rule name was changed during the discussion in the PR where this rule was introduced. ref: https://github.com/rust-lang/rust-clippy/pull/4231 changelog: none