Remove defaults for some shapes in some services

Adds an integration that removes the default value from certain
shapes in some services where the default value is 0, but the
service expects a value > 0.

.changes/190be92b-a106-476b-99b3-224a80f81d7d.json

@@ -0,0 +1,6 @@
+{
+    "id": "190be92b-a106-476b-99b3-224a80f81d7d",
+    "type": "bugfix",
+    "description": "**Breaking**: Make some types for EMR Serverless optional by removing default values",
+    "requiresMinorVersionBump": true
+}

codegen/smithy-aws-kotlin-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/RemoveDefaults.kt

@@ -0,0 +1,79 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package aws.sdk.kotlin.codegen.customization
+
+import software.amazon.smithy.codegen.core.CodegenException
+import software.amazon.smithy.kotlin.codegen.KotlinSettings
+import software.amazon.smithy.kotlin.codegen.integration.KotlinIntegration
+import software.amazon.smithy.kotlin.codegen.model.hasTrait
+import software.amazon.smithy.model.Model
+import software.amazon.smithy.model.shapes.AbstractShapeBuilder
+import software.amazon.smithy.model.shapes.MemberShape
+import software.amazon.smithy.model.shapes.Shape
+import software.amazon.smithy.model.shapes.ShapeId
+import software.amazon.smithy.model.traits.DefaultTrait
+import software.amazon.smithy.model.transform.ModelTransformer
+import software.amazon.smithy.utils.ToSmithyBuilder
+
+/**
+ * Removes the default value of certain shapes, and any member that target
+ * those shapes,for certain services. These default values may cause
+ * serialization, validation, or other unexpected issues.
+ */
+class RemoveDefaults : KotlinIntegration {
+    // Service shape id -> Shape id of each root shape to remove default values from.
+    private val removeDefaultsFrom = mapOf(
+        ShapeId.from("com.amazonaws.emrserverless#AwsToledoWebService") to setOf(
+            // Service expects value > 0
+            ShapeId.from("com.amazonaws.emrserverless#WorkerCounts"),
+        ),
+    )
+
+    override val order: Byte = 0
+
+    override fun enabledForService(model: Model, settings: KotlinSettings): Boolean {
+        val serviceId = settings.service
+        return serviceId in removeDefaultsFrom
+    }
+
+    override fun preprocessModel(model: Model, settings: KotlinSettings): Model {
+        val serviceId = settings.service
+        val removeDefaultsFromShapes = removeDefaultsFrom[serviceId]
+            ?: throw CodegenException("expected $serviceId in removed defaults map")
+        return removeDefaults(model, removeDefaultsFromShapes)
+    }
+
+    fun removeDefaults(model: Model, fromShapes: Set<ShapeId>): Model {
+        val removedRootDefaults: MutableSet<ShapeId> = HashSet()
+        val removedRootDefaultsModel = ModelTransformer.create().mapShapes(model) {
+            if (shouldRemoveRootDefault(it, fromShapes)) {
+                removedRootDefaults.add(it.id)
+                removeDefault(it)
+            } else {
+                it
+            }
+        }
+
+        return ModelTransformer.create().mapShapes(removedRootDefaultsModel) {
+            if (shouldRemoveMemberDefault(it, removedRootDefaults)) {
+                removeDefault(it)
+            } else {
+                it
+            }
+        }
+    }
+
+    private fun shouldRemoveRootDefault(shape: Shape, removeDefaultsFrom: Set<ShapeId>): Boolean =
+        shape !is MemberShape && removeDefaultsFrom.contains(shape.id) && shape.hasTrait<DefaultTrait>()
+
+    private fun shouldRemoveMemberDefault(shape: Shape, removeDefaultsFrom: Set<ShapeId>): Boolean =
+        shape is MemberShape && removeDefaultsFrom.contains(shape.target) && shape.hasTrait<DefaultTrait>()
+
+    private fun removeDefault(shape: Shape): Shape =
+        ((shape as ToSmithyBuilder<*>).toBuilder() as AbstractShapeBuilder<*, *>)
+            .removeTrait(DefaultTrait.ID)
+            .build()
+}

codegen/smithy-aws-kotlin-codegen/src/main/resources/META-INF/services/software.amazon.smithy.kotlin.codegen.integration.KotlinIntegration

@@ -31,3 +31,4 @@ aws.sdk.kotlin.codegen.customization.s3.HostPrefixRequestRouteFilter
 aws.sdk.kotlin.codegen.customization.s3.UnwrappedXmlOutputIntegration
 aws.sdk.kotlin.codegen.customization.ClockSkew
 aws.sdk.kotlin.codegen.customization.ec2.EC2MakePrimitivesOptional
+aws.sdk.kotlin.codegen.customization.RemoveDefaults

codegen/smithy-aws-kotlin-codegen/src/test/kotlin/aws/sdk/kotlin/codegen/customization/RemoveDefaultsTest.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package aws.sdk.kotlin.codegen.customization
+
+import org.junit.jupiter.api.Test
+import software.amazon.smithy.kotlin.codegen.model.hasTrait
+import software.amazon.smithy.kotlin.codegen.test.toSmithyModel
+import software.amazon.smithy.model.shapes.ShapeId
+import software.amazon.smithy.model.traits.DefaultTrait
+import kotlin.test.assertFalse
+
+class RemoveDefaultsTest {
+    @Test
+    fun removesDefaults() {
+        val model = """
+            ${"$"}version: "2.0"
+            
+            namespace test
+            
+            structure Foo {
+                bar: Bar = 0
+            }
+            
+            @default(0)
+            integer Bar
+            
+        """.toSmithyModel()
+
+        val transformed = RemoveDefaults().removeDefaults(model, setOf(ShapeId.from("test#Bar")))
+        val member = transformed.expectShape(ShapeId.from("test#Foo\$bar"))
+        assertFalse(member.hasTrait<DefaultTrait>())
+        val root = transformed.expectShape(ShapeId.from("test#Bar"))
+        assertFalse(root.hasTrait<DefaultTrait>())
+    }
+}