packaging: Implement JLinkTask

The JLinkTask parses JDeps' output and generates a runtime image for
jpackage.

build-logic/packaging/src/main/kotlin/bisq/gradle/packaging/JLinkTask.kt

@@ -0,0 +1,61 @@
+package bisq.gradle.packaging
+
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.tasks.InputDirectory
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.TaskAction
+import java.util.concurrent.TimeUnit
+
+abstract class JLinkTask : DefaultTask() {
+
+    @get:InputDirectory
+    abstract val jdkDirectory: DirectoryProperty
+
+    @get:InputDirectory
+    abstract val javaFxJmodsDirectory: DirectoryProperty
+
+    @get:InputFile
+    abstract val jDepsOutputFile: RegularFileProperty
+
+    @get:OutputDirectory
+    abstract val outputDirectory: DirectoryProperty
+
+    @TaskAction
+    fun run() {
+        // jlink expects non-existent output directory
+        val outputDirectoryFile = outputDirectory.asFile.get()
+        outputDirectoryFile.deleteRecursively()
+
+        val jLinkPath = jdkDirectory.asFile.get().toPath().resolve("bin").resolve("jlink")
+        val processBuilder = ProcessBuilder(
+                jLinkPath.toAbsolutePath().toString(),
+
+                "--module-path", javaFxJmodsDirectory.asFile.get().absolutePath,
+                "--add-modules", parseUsedJavaModulesFromJDepsOutput(),
+
+                "--strip-native-commands",
+                "--no-header-files",
+                "--no-man-pages",
+                "--strip-debug",
+
+                "--output", outputDirectoryFile.absolutePath
+        )
+        processBuilder.inheritIO()
+
+        val process = processBuilder.start()
+        process.waitFor(2, TimeUnit.MINUTES)
+
+        val isSuccess = process.exitValue() == 0
+        if (!isSuccess) {
+            throw IllegalStateException("jlink couldn't create custom runtime.")
+        }
+    }
+
+    private fun parseUsedJavaModulesFromJDepsOutput(): String {
+        val readLines = jDepsOutputFile.asFile.get().readLines()
+        return readLines.joinToString(",")
+    }
+}