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+# v0.18.0
+
+## Config Block
+
+The `config_block` provided to the adapter must now return `nil`, `client` or a middleware wrapper around `client`.
+
+```ruby
+Faraday.new do |builder|
+	builder.adapter :async_http do |client|
+		# Option 1 (same as returning `nil`), use client as is:
+		client # Use `client` as is.
+		
+		# Option 2, wrap client in a middleware:
+		Async::HTTP::Middleware::LocationRedirector.new(client)
+	end
+end
+```