Generate Spring @ProjectedPayload Interface

[JamesPeters98]

When generating Resolver interfaces with lots of top level fields it can leave the method signatures very long.

Spring offers the use of @ProjectedPayload interfaces: https://docs.spring.io/spring-graphql/docs/current/reference/html/#controllers.schema-mapping.projectedpayload.argument

Ideally the resolvers would generate the projected interface inside or alongside the resolver interface, something like this:

    @MutationMapping
    CompletableFuture<Boolean> testMutation(TestMutationPayload payload, DataFetchingEnvironment env);

    @ProjectedPayload
    public interface TestMutationPayload {
        @NonNull BigDecimal amount();
        @NonNull String code();
        int lineNumber();
        OtherType type();
    }

For a schema that looks like this:

testMutation(
        amount: BigDecimal!,
        code: String!,
        lineNumber: Int!,
        type: OtherType = TEST
    ): Boolean!

[JamesPeters98]

Thinking about it, this would probably be useful to generate completely separately to the Resovler interfaces so you can just rely on the generated Payloads without using the generated resovlers.