support custom scalars

[jexp]

• todo how do we to the mapping / coercion?
• should that be a client side concern
• do we need additional directives or @cypher?
• can we go with some valueOf/toString from the JVM?

see in the javascript library

[jexp]

In the plugin we currently just pass-through

https://github.com/neo4j-graphql/neo4j-graphql/blob/3.5/src/main/kotlin/org/neo4j/graphql/GraphQLSchemaBuilder.kt#L414

https://github.com/neo4j-graphql/neo4j-graphql/blob/3.5/src/test/java/org/neo4j/graphql/ScalarTest.kt#L33-L96

[jexp]

optional perhaps with a directive ....

scalar Foo @convert(parse:"return toInteger(value)", format: "....")

also talk to Will / Michael

[jexp]

Only do pass-through with NoOpCocerce for now

[jexp]

Perhaps it already works out of the box, whcih we should see with a simple test.