Code generation using gradle plugin fails for NonNullType of List with empty list as default value (Version: graphql-java-codegen 1.7.3)

[IntiG]

Issue Description

Code generation using gradle plugin from graphql schema fails with this message:
Unexpected array default value for non-list type

Here is a snippet of the schema, I actually identified the part that fails:

type Query {
  "Select error events"
  select_error(
    "Maximum number of objects to return"
    first: Int! = 1000, 
    "List of possible options for the group by"
    group_by: [bus_error_groupby_enum!]! = []
  ): [error_activity]

the part that causes the issue is this:
group_by: [bus_error_groupby_enum!]! = []
changing it to this, gets rid of the issue:
group_by: [bus_error_groupby_enum!] = []

I tried the code to understand where it came from and apparently it is in
src/main/java/com/kobylynskyi/graphql/codegen/mapper/DefaultValueMapper.java

  private static String mapArray(MappingContext mappingContext, ArrayValue defaultValue, Type<?> graphQLType) {
        if (!(graphQLType instanceof ListType)) {
            throw new IllegalArgumentException("Unexpected array default value for non-list type");
        }

the defaultValue is a list while the type is actually not a ListType but a NonNullType

Steps to Reproduce

Add this to your schema and try to generate the code
group_by: [bus_error_groupby_enum!]! = []

Expected Result

I would expect a NonNullType of List to accept a default value of type List

Actual Result

Code generation using gradle plugin from graphql schema fails with this message:
Unexpected array default value for non-list type

Your Environment and Setup

• graphql-java-codegen: 1.7.3
• Build tool: Gradle
• Java tool: AdoptOpenJdk 11.0.6.10-hotspot
• Mapping Config:

graphqlCodegen {
    graphqlSchemaPaths = ["$projectDir/generated_schema.graphqls".toString()]
    outputDir = new File("$buildDir/generated")
    generateApis = true
    generateToString = true
    modelValidationAnnotation = ""
    generateRequests = true
}

[kobylynskyi]

@IntiG, thanks for a very explanatory description!
The fix is on the way and should be available this week as part of version 2.0.0.

[kobylynskyi]

Please also note that generateRequests was deprecated in favor of generateClient (see #169)

[IntiG]

@kobylynskyi thanks for this very cool plugin of yours, I like how readable and easy it is to build queries with the generated code :)
I'll switch to using generateClient thanks for letting me know.

On a side note, may I ask if you plan on supporting sbt plugin again? I know that there was one but not published and with a bit less "capabilities".