Add type definitions to schema extensions

[smyrick]

TS Compiler error

Because the type schema.extensions is unknown the TS compiler is failing because it doesn't know for sure if schema.extensions.apollo is an object. If it is not, we can not perform a spread on it.

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[cpeacock]

@clenfest mind taking a quick look at this at some point? seems fine to me but you are more knowledgeable

[trevor-scheer]

@smyrick @clenfest This is just a fly-by comment and it's possible I'm misunderstanding something here, but I would've expected something similar to what subgraph-js does by extending the extensions type as the outcome:

federation/subgraph-js/src/schemaExtensions.ts

Lines 13 to 18 in 4e3c161

	declare module 'graphql/type/definition' {
	interface GraphQLObjectTypeExtensions<_TSource = any, _TContext = any> {
	apollo?: {
	subgraph?: ApolloSubgraphExtensions<_TContext>;
	};
	}

[smyrick]

@trevor-scheer There is that type declared already:

federation/gateway-js/src/typings/graphql.ts

Lines 37 to 43 in 2946bdf

	declare module 'graphql/type/schema' {
	interface GraphQLSchemaExtensions {
	apollo?: {
	gateway?: ApolloGatewayExtensions;
	}
	}
	}

And I am using it here:

federation/gateway-js/src/schema-helper/addExtensions.ts

Line 2 in 2946bdf

import { GraphQLSchemaExtensions } from 'graphql/type/schema';