type not found in schema

[KMUS]

configuration

<dependency>
    <groupId>org.eclipse.microprofile.graphql</groupId>
    <artifactId>microprofile-graphql-api</artifactId>
    <version>1.0-M5</version>
</dependency>
<dependency>
    <groupId>io.leangen.graphql</groupId>
    <artifactId>graphql-spqr-module-microprofile</artifactId>
    <version>1.0-SNAPSHOT</version>
    <scope>system</scope>
    <systemPath>${basedir}/lib/graphql-spqr-module-microprofile-1.0-SNAPSHOT.jar</systemPath>
</dependency>

schema = new GraphQLSchemaGenerator()
                        .withModules(new MicroProfileModule())
...

models

class Bar {
}

class Foo {
    Bar bar; // setter and getter are omitted
}

endpoint

@Mutation("create")
public String create(Foo foo) {
    return "string";
}

A side reload with GraphiQL always gives:

type BarInput not found in schema

This only happens with nested user-defined types, whether as a class or an enumeration.