feat: [k2] add support for data types inherited from extended interface

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/DgsClient.kt

@@ -0,0 +1,14 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected
+
+import com.netflix.graphql.dgs.client.codegen.InputValueSerializerInterface
+import com.netflix.graphql.dgs.codegen.GraphQLProjection
+import com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected.client.QueryProjection
+import graphql.language.OperationDefinition
+import kotlin.String
+
+public object DgsClient {
+  public fun buildQuery(inputValueSerializer: InputValueSerializerInterface? = null,
+      _projection: QueryProjection.() -> QueryProjection): String =
+      GraphQLProjection.asQuery(OperationDefinition.Operation.QUERY,
+      QueryProjection(inputValueSerializer), _projection)
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/DgsConstants.kt

@@ -0,0 +1,35 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected
+
+import kotlin.String
+
+public object DgsConstants {
+  public const val QUERY_TYPE: String = "Query"
+
+  public object QUERY {
+    public const val TYPE_NAME: String = "Query"
+
+    public const val People: String = "people"
+  }
+
+  public object EMPLOYEE {
+    public const val TYPE_NAME: String = "Employee"
+
+    public const val Firstname: String = "firstname"
+
+    public const val Lastname: String = "lastname"
+
+    public const val Company: String = "company"
+
+    public const val Age: String = "age"
+  }
+
+  public object PERSON {
+    public const val TYPE_NAME: String = "Person"
+
+    public const val Firstname: String = "firstname"
+
+    public const val Lastname: String = "lastname"
+
+    public const val Age: String = "age"
+  }
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/client/EmployeeProjection.kt

@@ -0,0 +1,32 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected.client
+
+import com.netflix.graphql.dgs.client.codegen.InputValueSerializerInterface
+import com.netflix.graphql.dgs.codegen.GraphQLProjection
+
+public class EmployeeProjection(
+  inputValueSerializer: InputValueSerializerInterface? = null,
+) : GraphQLProjection(inputValueSerializer) {
+  public val firstname: EmployeeProjection
+    get() {
+      field("firstname")
+      return this
+    }
+
+  public val lastname: EmployeeProjection
+    get() {
+      field("lastname")
+      return this
+    }
+
+  public val company: EmployeeProjection
+    get() {
+      field("company")
+      return this
+    }
+
+  public val age: EmployeeProjection
+    get() {
+      field("age")
+      return this
+    }
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/client/PersonProjection.kt

@@ -0,0 +1,26 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected.client
+
+import com.netflix.graphql.dgs.client.codegen.InputValueSerializerInterface
+import com.netflix.graphql.dgs.codegen.GraphQLProjection
+
+public class PersonProjection(
+  inputValueSerializer: InputValueSerializerInterface? = null,
+) : GraphQLProjection(inputValueSerializer) {
+  public val firstname: PersonProjection
+    get() {
+      field("firstname")
+      return this
+    }
+
+  public val lastname: PersonProjection
+    get() {
+      field("lastname")
+      return this
+    }
+
+  public fun onEmployee(_projection: EmployeeProjection.() -> EmployeeProjection):
+      PersonProjection {
+    fragment("Employee", EmployeeProjection(), _projection)
+    return this
+  }
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/client/QueryProjection.kt

@@ -0,0 +1,15 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected.client
+
+import com.netflix.graphql.dgs.client.codegen.InputValueSerializerInterface
+import com.netflix.graphql.dgs.codegen.GraphQLProjection
+import kotlin.String
+
+public class QueryProjection(
+  inputValueSerializer: InputValueSerializerInterface? = null,
+) : GraphQLProjection(inputValueSerializer) {
+  public fun people(_alias: String? = null, _projection: PersonProjection.() -> PersonProjection):
+      QueryProjection {
+    field(_alias, "people", PersonProjection(inputValueSerializer), _projection)
+    return this
+  }
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/types/Employee.kt

@@ -0,0 +1,101 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected.types
+
+import com.fasterxml.jackson.`annotation`.JsonIgnoreProperties
+import com.fasterxml.jackson.`annotation`.JsonProperty
+import com.fasterxml.jackson.`annotation`.JsonTypeInfo
+import com.fasterxml.jackson.databind.`annotation`.JsonDeserialize
+import com.fasterxml.jackson.databind.`annotation`.JsonPOJOBuilder
+import java.lang.IllegalStateException
+import kotlin.Int
+import kotlin.String
+import kotlin.Suppress
+import kotlin.jvm.JvmName
+
+@JsonTypeInfo(use = JsonTypeInfo.Id.NONE)
+@JsonDeserialize(builder = Employee.Builder::class)
+public class Employee(
+  firstname: () -> String = firstnameDefault,
+  lastname: () -> String? = lastnameDefault,
+  company: () -> String? = companyDefault,
+  age: () -> Int = ageDefault,
+) : Person {
+  private val __firstname: () -> String = firstname
+
+  private val __lastname: () -> String? = lastname
+
+  private val __company: () -> String? = company
+
+  private val __age: () -> Int = age
+
+  @Suppress("INAPPLICABLE_JVM_NAME")
+  @get:JvmName("getFirstname")
+  override val firstname: String
+    get() = __firstname.invoke()
+
+  @Suppress("INAPPLICABLE_JVM_NAME")
+  @get:JvmName("getLastname")
+  override val lastname: String?
+    get() = __lastname.invoke()
+
+  @get:JvmName("getCompany")
+  public val company: String?
+    get() = __company.invoke()
+
+  @Suppress("INAPPLICABLE_JVM_NAME")
+  @get:JvmName("getAge")
+  override val age: Int
+    get() = __age.invoke()
+
+  public companion object {
+    private val firstnameDefault: () -> String = 
+        { throw IllegalStateException("Field `firstname` was not requested") }
+
+    private val lastnameDefault: () -> String? = 
+        { throw IllegalStateException("Field `lastname` was not requested") }
+
+    private val companyDefault: () -> String? = 
+        { throw IllegalStateException("Field `company` was not requested") }
+
+    private val ageDefault: () -> Int = 
+        { throw IllegalStateException("Field `age` was not requested") }
+  }
+
+  @JsonPOJOBuilder
+  @JsonIgnoreProperties("__typename")
+  public class Builder {
+    private var firstname: () -> String = firstnameDefault
+
+    private var lastname: () -> String? = lastnameDefault
+
+    private var company: () -> String? = companyDefault
+
+    private var age: () -> Int = ageDefault
+
+    @JsonProperty("firstname")
+    public fun withFirstname(firstname: String): Builder = this.apply {
+      this.firstname = { firstname }
+    }
+
+    @JsonProperty("lastname")
+    public fun withLastname(lastname: String?): Builder = this.apply {
+      this.lastname = { lastname }
+    }
+
+    @JsonProperty("company")
+    public fun withCompany(company: String?): Builder = this.apply {
+      this.company = { company }
+    }
+
+    @JsonProperty("age")
+    public fun withAge(age: Int): Builder = this.apply {
+      this.age = { age }
+    }
+
+    public fun build(): Employee = Employee(
+      firstname = firstname,
+      lastname = lastname,
+      company = company,
+      age = age,
+    )
+  }
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/types/Person.kt

@@ -0,0 +1,30 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected.types
+
+import com.fasterxml.jackson.`annotation`.JsonSubTypes
+import com.fasterxml.jackson.`annotation`.JsonTypeInfo
+import kotlin.Int
+import kotlin.String
+import kotlin.Suppress
+import kotlin.jvm.JvmName
+
+@JsonTypeInfo(
+  use = JsonTypeInfo.Id.NAME,
+  include = JsonTypeInfo.As.PROPERTY,
+  property = "__typename",
+)
+@JsonSubTypes(value = [
+  JsonSubTypes.Type(value = Employee::class, name = "Employee")
+])
+public sealed interface Person {
+  @Suppress("INAPPLICABLE_JVM_NAME")
+  @get:JvmName("getFirstname")
+  public val firstname: String
+
+  @Suppress("INAPPLICABLE_JVM_NAME")
+  @get:JvmName("getLastname")
+  public val lastname: String?
+
+  @Suppress("INAPPLICABLE_JVM_NAME")
+  @get:JvmName("getAge")
+  public val age: Int
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/expected/types/Query.kt

@@ -0,0 +1,42 @@
+package com.netflix.graphql.dgs.codegen.cases.dataClassWithExtendedInterfaceInheritance.expected.types
+
+import com.fasterxml.jackson.`annotation`.JsonIgnoreProperties
+import com.fasterxml.jackson.`annotation`.JsonProperty
+import com.fasterxml.jackson.`annotation`.JsonTypeInfo
+import com.fasterxml.jackson.databind.`annotation`.JsonDeserialize
+import com.fasterxml.jackson.databind.`annotation`.JsonPOJOBuilder
+import java.lang.IllegalStateException
+import kotlin.collections.List
+import kotlin.jvm.JvmName
+
+@JsonTypeInfo(use = JsonTypeInfo.Id.NONE)
+@JsonDeserialize(builder = Query.Builder::class)
+public class Query(
+  people: () -> List<Person?>? = peopleDefault,
+) {
+  private val __people: () -> List<Person?>? = people
+
+  @get:JvmName("getPeople")
+  public val people: List<Person?>?
+    get() = __people.invoke()
+
+  public companion object {
+    private val peopleDefault: () -> List<Person?>? = 
+        { throw IllegalStateException("Field `people` was not requested") }
+  }
+
+  @JsonPOJOBuilder
+  @JsonIgnoreProperties("__typename")
+  public class Builder {
+    private var people: () -> List<Person?>? = peopleDefault
+
+    @JsonProperty("people")
+    public fun withPeople(people: List<Person?>?): Builder = this.apply {
+      this.people = { people }
+    }
+
+    public fun build(): Query = Query(
+      people = people,
+    )
+  }
+}

graphql-dgs-codegen-core/src/integTest/kotlin/com/netflix/graphql/dgs/codegen/cases/dataClassWithExtendedInterfaceInheritance/schema.graphql

@@ -0,0 +1,22 @@
+type Query {
+  people: [Person]
+}
+
+interface Person {
+  firstname: String!
+  lastname: String
+}
+
+type Employee implements Person {
+  firstname: String!
+  lastname: String
+  company: String
+}
+
+extend interface Person {
+  age: Int!
+}
+
+extend type Employee {
+  age: Int!
+}

graphql-dgs-codegen-core/src/main/kotlin/com/netflix/graphql/dgs/codegen/generators/kotlin2/Kotlin2TypeLookup.kt

@@ -143,7 +143,8 @@ class Kotlin2TypeLookup(
      */
     private val interfaceFields: Map<String, List<String>> = document
         .getDefinitionsOfType(InterfaceTypeDefinition::class.java)
-        .associate { i -> i.name to i.fieldDefinitions.map { it.name } }
+        .groupBy(keySelector = { it.name }, valueTransform = { it.fieldDefinitions })
+        .mapValues { e -> e.value.flatten().map { i -> i.name } }
 
     /**
      * A map of interfaces to the types that implement them