Variables are coerced twice during an execution when a field validation instrumentation is active

[jenssuhr]

Describe the bug
It looks like variables are coerced twice during an execution using graphql-java 16.2, once in execute and once in validateFieldsAndArguments. This breaks e.g. enums with non-default names.

Variables are first coerced here, then added to the execution context.
In FieldValidationSupport, the QueryTraverser is initialized with those variables from the execution context and coerces them again here.

To Reproduce
If you have an enum value defined like this

GraphQLEnumType.newEnum()
    .name("MyEnum")
    .description("My enum with all lowercase names.")
    .values(
        MyEnum.values().map {
            GraphQLEnumValueDefinition.newEnumValueDefinition()
                .name(it.getLowerCaseName())
                .value(it)
                .build()
        }
    ).build()

the first coercion works correctly, but the second one fails.

[dondonz]

Hi @jenssuhr,

I'm trying to investigate the issue but I can't reproduce the error. Could you please help me by expanding on your example?

Could you please paste here:

1. an example query,
2. the field validation instrumentation(s) used, and
3. the name of the error when the second coercion failed

[jenssuhr]

Hi, thanks for investigating! I'll try to add an example as soon as possible.

[jenssuhr]

I just noticed that we're not using the field validation correctly. Instead of using SimpleFieldValidation and adding rules, we were using a separate FieldValidationInstrumentation for each rule and chaining them together using ChainedInstrumentation. Fixing that will probably also fix this issue.
Thank you for your help!