private static TypeSignature getReturnTypeSignature(Method method) {
        if (isKFunction(method)) {
            if (isReturnTypeNothing(method)) {
                return toTypeSignature(kFunctionReturnType(method));
            }
            return toTypeSignature(kFunctionGenericReturnType(method));
        }
        return toTypeSignature(method.getGenericReturnType());
    }
A {@link DocServicePlugin} implementation that supports the {@link AnnotatedService}.
core/src/main/java/com/linecorp/armeria/internal/server/annotation/AnnotatedDocServicePlugin.java