refactor(cargo): Migrate manifest parsing to kotlinx-serialization

Note that kotlinx-serialization requires optional properties to have
default values even if they are nullable.

Signed-off-by: Sebastian Schuberth <[email protected]>

Author: sschuberth

plugins/package-managers/cargo/build.gradle.kts

@@ -17,6 +17,8 @@
  * License-Filename: LICENSE
  */
 
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
 plugins {
     // Apply precompiled plugins.
     id("ort-library-conventions")
@@ -40,10 +42,18 @@ dependencies {
     implementation(project(":utils:ort-utils"))
     implementation(project(":utils:spdx-utils"))
 
-    implementation(libs.jacksonDatabind)
-    implementation(libs.jacksonModuleKotlin)
-    implementation(libs.kotlinxSerializationCore)
+    implementation(libs.bundles.kotlinxSerialization)
     implementation(libs.tomlkt)
 
     funTestImplementation(testFixtures(project(":analyzer")))
 }
+
+tasks.withType<KotlinCompile>().configureEach {
+    val customCompilerArgs = listOf(
+        "-opt-in=kotlinx.serialization.ExperimentalSerializationApi"
+    )
+
+    compilerOptions {
+        freeCompilerArgs.addAll(customCompilerArgs)
+    }
+}

plugins/package-managers/cargo/src/main/kotlin/Cargo.kt

@@ -21,10 +21,11 @@
 
 package org.ossreviewtoolkit.plugins.packagemanagers.cargo
 
-import com.fasterxml.jackson.module.kotlin.readValue
-
 import java.io.File
 
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonNamingStrategy
+
 import net.peanuuutz.tomlkt.Toml
 import net.peanuuutz.tomlkt.decodeFromNativeReader
 
@@ -46,7 +47,6 @@ import org.ossreviewtoolkit.model.RemoteArtifact
 import org.ossreviewtoolkit.model.Scope
 import org.ossreviewtoolkit.model.config.AnalyzerConfiguration
 import org.ossreviewtoolkit.model.config.RepositoryConfiguration
-import org.ossreviewtoolkit.model.jsonMapper
 import org.ossreviewtoolkit.model.orEmpty
 import org.ossreviewtoolkit.utils.common.CommandLineTool
 import org.ossreviewtoolkit.utils.common.splitOnWhitespace
@@ -56,6 +56,11 @@ import org.ossreviewtoolkit.utils.ort.ProcessedDeclaredLicense
 import org.ossreviewtoolkit.utils.spdx.SpdxConstants
 import org.ossreviewtoolkit.utils.spdx.SpdxOperator
 
+private val json = Json {
+    ignoreUnknownKeys = true
+    namingStrategy = JsonNamingStrategy.SnakeCase
+}
+
 private val toml = Toml { ignoreUnknownKeys = true }
 
 /**
@@ -164,7 +169,7 @@ class Cargo(
 
         val workingDir = definitionFile.parentFile
         val metadataProcess = run(workingDir, "metadata", "--format-version=1")
-        val metadata = jsonMapper.readValue<CargoMetadata>(metadataProcess.stdout)
+        val metadata = json.decodeFromString<CargoMetadata>(metadataProcess.stdout)
         val hashes = readHashes(resolveLockfile(metadata))
 
         val packages = metadata.packages.associateBy(

plugins/package-managers/cargo/src/main/kotlin/CargoMetadata.kt

@@ -19,45 +19,46 @@
 
 package org.ossreviewtoolkit.plugins.packagemanagers.cargo
 
-import com.fasterxml.jackson.annotation.JsonIgnoreProperties
+import kotlinx.serialization.Serializable
 
 /**
  * See https://doc.rust-lang.org/cargo/commands/cargo-metadata.html.
  */
-@JsonIgnoreProperties(ignoreUnknown = true)
+@Serializable
 internal data class CargoMetadata(
     val packages: List<Package>,
     val workspaceMembers: List<String>,
     val resolve: Resolve,
     val workspaceRoot: String
 ) {
-    @JsonIgnoreProperties(ignoreUnknown = true)
+    @Serializable
     data class Package(
         val name: String,
         val version: String,
         val id: String,
-        val license: String?,
-        val licenseFile: String?,
-        val description: String?,
-        val source: String?,
-        val dependencies: List<Dependency>,
-        val authors: List<String>,
-        val repository: String?,
-        val homepage: String?
+        val license: String? = null,
+        val licenseFile: String? = null,
+        val description: String? = null,
+        val source: String? = null,
+        val dependencies: List<Dependency> = emptyList(),
+        val authors: List<String> = emptyList(),
+        val repository: String? = null,
+        val homepage: String? = null
     )
 
-    @JsonIgnoreProperties(ignoreUnknown = true)
+    @Serializable
     data class Dependency(
         val name: String,
-        val kind: String?
+        val kind: String? = null
     )
 
+    @Serializable
     data class Resolve(
         val nodes: List<Node>,
-        val root: String?
+        val root: String? = null
     )
 
-    @JsonIgnoreProperties(ignoreUnknown = true)
+    @Serializable
     data class Node(
         val id: String,
         val dependencies: List<String>