refactor(composer): Port the deserialization code from Jackson to KxS

Note that KxS requires to explicitly state default values even for
nullable types, while Jackson implicitly defaults to null for nullable
types.

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

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

@@ -20,6 +20,9 @@
 plugins {
     // Apply precompiled plugins.
     id("ort-library-conventions")
+
+    // Apply third-party plugins.
+    alias(libs.plugins.kotlinSerialization)
 }
 
 dependencies {
@@ -37,9 +40,8 @@ dependencies {
     implementation(projects.utils.ortUtils)
     implementation(projects.utils.spdxUtils)
 
-    implementation(libs.jackson.core)
-    implementation(libs.jackson.databind)
-    implementation(libs.jackson.module.kotlin)
+    implementation(libs.kotlinx.serialization.core)
+    implementation(libs.kotlinx.serialization.json)
 
     funTestImplementation(testFixtures(projects.analyzer))
 }

plugins/package-managers/composer/src/main/kotlin/Model.kt

@@ -19,60 +19,60 @@
 
 package org.ossreviewtoolkit.plugins.packagemanagers.composer
 
-import com.fasterxml.jackson.annotation.JsonIgnoreProperties
-import com.fasterxml.jackson.annotation.JsonProperty
-import com.fasterxml.jackson.module.kotlin.readValue
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
 
-import org.ossreviewtoolkit.model.jsonMapper
-
-@JsonIgnoreProperties(ignoreUnknown = true)
+@Serializable
 internal data class Lockfile(
     val packages: List<PackageInfo> = emptyList(),
-    @JsonProperty("packages-dev")
+    @SerialName("packages-dev")
     val packagesDev: List<PackageInfo> = emptyList()
 )
 
-@JsonIgnoreProperties(ignoreUnknown = true)
+@Serializable
 internal data class PackageInfo(
-    val name: String?,
+    val name: String? = null,
     // See https://getcomposer.org/doc/04-schema.md#version.
-    val version: String?,
-    val homepage: String?,
-    val description: String?,
+    val version: String? = null,
+    val homepage: String? = null,
+    val description: String? = null,
     val source: Source? = null,
     val authors: List<Author> = emptyList(),
     val license: List<String> = emptyList(),
     val provide: Map<String, String> = emptyMap(),
     val replace: Map<String, String> = emptyMap(),
     val require: Map<String, String> = emptyMap(),
-    @JsonProperty("require-dev")
+    @SerialName("require-dev")
     val requireDev: Map<String, String> = emptyMap(),
     val dist: Dist? = null
 ) {
-    @JsonIgnoreProperties(ignoreUnknown = true)
+    @Serializable
     data class Author(
         val name: String? = null,
         val email: String? = null,
         val homepage: String? = null,
         val role: String? = null
     )
 
-    @JsonIgnoreProperties(ignoreUnknown = true)
+    @Serializable
     data class Source(
         val type: String? = null,
         val url: String? = null,
         val reference: String? = null
     )
 
-    @JsonIgnoreProperties(ignoreUnknown = true)
+    @Serializable
     data class Dist(
-        val type: String?,
-        val url: String?,
-        val reference: String?,
-        val shasum: String?
+        val type: String? = null,
+        val url: String? = null,
+        val reference: String? = null,
+        val shasum: String? = null
     )
 }
 
-internal fun parseLockfile(json: String): Lockfile = jsonMapper.readValue<Lockfile>(json)
+private val JSON = Json { ignoreUnknownKeys = true }
+
+internal fun parseLockfile(json: String): Lockfile = JSON.decodeFromString<Lockfile>(json)
 
-internal fun parsePackageInfo(json: String): PackageInfo = jsonMapper.readValue<PackageInfo>(json)
+internal fun parsePackageInfo(json: String): PackageInfo = JSON.decodeFromString<PackageInfo>(json)