Ensure reserved words are escaped in generated inputs (#604)

* Ensure reserved words are escaped in generated inputs

* Address linting

Author: mbossenbroek

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

@@ -0,0 +1,3 @@
+package com.netflix.graphql.dgs.codegen.cases.inputWithReservedWord.expected
+
+public object DgsClient

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

@@ -0,0 +1,11 @@
+package com.netflix.graphql.dgs.codegen.cases.inputWithReservedWord.expected
+
+import kotlin.String
+
+public object DgsConstants {
+  public object SAMPLEINPUT {
+    public const val TYPE_NAME: String = "SampleInput"
+
+    public const val Return: String = "return"
+  }
+}

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

@@ -0,0 +1,13 @@
+package com.netflix.graphql.dgs.codegen.cases.inputWithReservedWord.expected.types
+
+import com.netflix.graphql.dgs.codegen.GraphQLInput
+import kotlin.Any
+import kotlin.Pair
+import kotlin.String
+import kotlin.collections.List
+
+public class SampleInput(
+  public val `return`: String,
+) : GraphQLInput() {
+  public override fun fields(): List<Pair<String, Any?>> = listOf("return" to `return`)
+}

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

@@ -0,0 +1,3 @@
+input SampleInput {
+  return: String!
+}

graphql-dgs-codegen-core/src/main/kotlin/com/netflix/graphql/dgs/codegen/generators/kotlin2/GenerateKotlin2InputTypes.kt

@@ -27,6 +27,7 @@ import com.netflix.graphql.dgs.codegen.generators.shared.SchemaExtensionsUtils.f
 import com.netflix.graphql.dgs.codegen.generators.shared.excludeSchemaTypeExtension
 import com.netflix.graphql.dgs.codegen.shouldSkip
 import com.squareup.kotlinpoet.ClassName
+import com.squareup.kotlinpoet.CodeBlock
 import com.squareup.kotlinpoet.FileSpec
 import com.squareup.kotlinpoet.FunSpec
 import com.squareup.kotlinpoet.KModifier
@@ -120,10 +121,12 @@ fun generateKotlin2InputTypes(
                                 )
                             )
                         )
-                        .addStatement(
-                            "return listOf(${
-                            fields.joinToString(", ") { """"${it.name}" to ${it.name}""" }
-                            })"
+                        .addCode(
+                            fields.let { fs ->
+                                val builder = CodeBlock.builder().add("return listOf(")
+                                fs.forEachIndexed { i, f -> builder.add("%S to %N%L", f.name, f.name, if (i < fs.size.dec()) ", " else "") }
+                                builder.add(")").build()
+                            }
                         )
                         .build()
                 )