chore(opossum reporter): migrate serialization to kotlinx

Migrates the OpossumReporter plugin away from Jackson serialization
to use kotlinx serialization. To get properly typed data structures for
serialization the previous untyped Map<*, *> are substituted by
properly typed data classes. This leads to the creation of an
OpossumInputCreator class that holds intermediate data structures
needed for processing of the Reporter input.

Signed-off-by: alexzurbonsen <[email protected]>

plugins/reporters/opossum/build.gradle.kts

@@ -20,6 +20,9 @@
 plugins {
     // Apply precompiled plugins.
     id("ort-plugin-conventions")
+
+    // Apply third-party plugins.
+    alias(libs.plugins.kotlinSerialization)
 }
 
 dependencies {
@@ -33,6 +36,6 @@ dependencies {
     implementation(projects.utils.ortUtils)
     implementation(projects.utils.spdxUtils)
 
-    implementation(libs.jackson.annotations)
-    implementation(libs.jackson.databind)
+    implementation(libs.kotlinx.serialization.core)
+    implementation(libs.kotlinx.serialization.json)
 }

plugins/reporters/opossum/src/funTest/kotlin/OpossumReporterFunTest.kt

@@ -19,14 +19,17 @@
 
 package org.ossreviewtoolkit.plugins.reporters.opossum
 
-import com.fasterxml.jackson.databind.json.JsonMapper
+import kotlinx.serialization.json.Json
 
 import io.kotest.core.TestConfiguration
 import io.kotest.core.spec.style.WordSpec
 import io.kotest.engine.spec.tempdir
-import io.kotest.matchers.sequences.shouldContain
+import io.kotest.matchers.collections.shouldContain
 import io.kotest.matchers.shouldBe
 import io.kotest.matchers.string.shouldContain
+import kotlinx.serialization.json.jsonArray
+import kotlinx.serialization.json.jsonObject
+import kotlinx.serialization.json.jsonPrimitive
 
 import org.ossreviewtoolkit.model.OrtResult
 import org.ossreviewtoolkit.plugins.api.PluginConfig
@@ -45,15 +48,24 @@ class OpossumReporterFunTest : WordSpec({
         }
 
         "create a parseable result and contain some expected values" {
-            with(JsonMapper().readTree(reportStr)) {
-                isObject shouldBe true
-                get("metadata").get("projectId").asText() shouldBe "0"
-                get("attributionBreakpoints").size() shouldBe 4
-                get("externalAttributionSources").size() shouldBe 7
-                get("resourcesToAttributions").fieldNames().asSequence() shouldContain
-                    "/analyzer/src/funTest/assets/projects/synthetic/gradle/lib/build.gradle/" +
-                    "compile/org.apache.commons/[email protected]/dependencies/org.apache.commons/[email protected]"
-            }
+            val json = Json.parseToJsonElement(reportStr).jsonObject
+
+            json["metadata"]?.jsonObject?.get("projectId")?.jsonPrimitive?.content shouldBe "0"
+            json["resources"]?.jsonObject?.size shouldBe 2
+            json["attributionBreakpoints"]?.jsonArray?.size shouldBe 4
+            json["externalAttributionSources"]?.jsonObject?.size shouldBe 7
+            json["frequentLicenses"]?.jsonArray?.size shouldBe 666
+            json["resourcesToAttributions"]?.jsonObject?.size shouldBe 13
+
+            val resourceRoots = json["resources"]?.jsonObject?.keys ?: emptySet()
+            resourceRoots shouldBe setOf("analyzer", "project")
+            val projectResource = json["resources"]?.jsonObject?.get("project")
+            projectResource?.jsonObject?.size shouldBe 5
+            projectResource?.jsonObject?.get("file.kt")?.jsonPrimitive?.content shouldBe "1"
+
+            val resourcePaths = json["resourcesToAttributions"]?.jsonObject?.keys ?: emptySet()
+            resourcePaths shouldContain "/analyzer/src/funTest/assets/projects/synthetic/gradle/lib/build.gradle/" +
+                "compile/org.apache.commons/[email protected]/dependencies/org.apache.commons/[email protected]"
         }
     }
 })