Null literal is unsupported

[dh94]

currently in graphql-java we can't distinguish between provided nulls and unprovided values,
even worse - the query just fails
see the official graphql pr here
graphql/graphql-spec#83

[andimarek]

comment by @bbakerman:

We could extend the grammar to allow a NullValue to be captured in syntax eg:

field (arg : null)
The trick then would be how best to tell DataFetchers that the value is null literal versus not present

[ieugen]

@andimarek : java.util.Optional could do that, no ?

[bbakerman]

java.util.Optional would indeed do it

but we would have to change the current behaviour from

T argValue = environment.getArgument("arg")

to

Optional argValue = environment.getArgument("arg")

This would break all existing code. Its a tricky one

[ieugen]

As they say: If you wish to make an omelet... release version 4 :).

[andimarek]

see #434