The GraphQL spec supports interfaces implementing other interfaces: https://github.com/graphql/graphql-spec/pull/373 When using `graphql-schema-utilities` with the --includeDirectives flag set, the `implements ...` clause is removed from Interfaces in the merged schema. ## Example ### Input Schema ``` interface Node { id: ID! } interface FooNode implements Node { id: ID! foo: String } ``` ### Output Schema from `graphql-schema-utilities` with the --includeDirectives flag set ``` interface Node { id: ID! } interface FooNode { id: ID! foo: String } ```