class ActiveRecord::ConnectionAdapters::ConnectionPool

def connection_cache_key(thread)

Experimental RBS support (using type sampling data from the type_fusion project). 

def connection_cache_key: (Thread thread) -> Thread

This signature was generated using 201 samples from 3 applications.

JRuby users that use Fibers.
This hook-in method allows for easier monkey-patching fixes needed by
https://github.com/rails/rails/pull/14938#commitcomment-6601951
From the discussion on GitHub:
-- 
def connection_cache_key(thread)
  thread
end