TODO: overview of writing custom integrations
112.1 Writing Custom Route Predicate Factories
TODO: document writing Custom Route Predicate Factories
112.2 Writing Custom GatewayFilter Factories
TODO: document writing Custom GatewayFilter Factories
112.3 Writing Custom Global Filters
TODO: document writing Custom Global Filters
112.4 Writing Custom Route Locators and Writers
TODO: document writing Custom Route Locators and Writers