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StringSwitchTransformer
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‎.gitignore

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.gradle
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.idea
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build/

‎README.md

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@@ -54,6 +54,7 @@ recommended to only enable computeMaxs and disable controlflow obfuscation when
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* [X] [5]NumberEncrypt
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* [X] [5]FloatingPointEncrypt
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* [X] [5]StringEncrypt
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* [X] [3]StringSwitch
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### Redirect
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‎grunt-main/src/main/kotlin/net/spartanb312/grunt/process/Transformers.kt

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@@ -33,6 +33,7 @@ object Transformers : Collection<Transformer> by mutableListOf(
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ClonedClassTransformer order 10,
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TrashClassTransformer order 11,
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HWIDAuthenticatorTransformer order 12,
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StringSwitchTransformer order 18,
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//ControlflowTransformer order 20,
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StringEncryptTransformer order 30,
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NumberEncryptTransformer order 31,

‎grunt-main/src/main/kotlin/net/spartanb312/grunt/process/transformers/encrypt/StringSwitchTransformer.kt

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package net.spartanb312.grunt.process.transformers.encrypt
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import net.spartanb312.grunt.config.setting
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import net.spartanb312.grunt.process.MethodProcessor
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import net.spartanb312.grunt.process.Transformer
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import net.spartanb312.grunt.process.resource.ResourceCache
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import net.spartanb312.grunt.utils.builder.*
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import net.spartanb312.grunt.utils.count
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import net.spartanb312.grunt.utils.extensions.isInterface
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import net.spartanb312.grunt.utils.getRandomString
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import net.spartanb312.grunt.utils.logging.Logger
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import org.objectweb.asm.Opcodes
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import org.objectweb.asm.Type
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import org.objectweb.asm.tree.*
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import kotlin.random.Random
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object StringSwitchTransformer : Transformer("StringSwitch", category = Category.Encryption), MethodProcessor {
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private val times by setting("Intensity", 1)
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private val exclusion by setting("Exclusions", listOf())
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override fun ResourceCache.transform() {
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Logger.info(" - Encrypting strings...")
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val count = count {
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repeat(times) { t ->
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if (times > 1) Logger.info(" Encrypting strings ${t + 1} of $times times")
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nonExcluded.asSequence()
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.filter { c -> !c.isInterface
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&& c.version > Opcodes.V1_5
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&& exclusion.none {
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c.name.startsWith(it) }
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}
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.forEach { classNode ->
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classNode.methods.toList().forEach { methodNode ->
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if (EncryptionMethod.FlattenedSwitch.transform(classNode, methodNode)) add()
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}
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}
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}
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}.get()
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Logger.info(" Encrypted $count strings")
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}
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override fun transformMethod(owner: ClassNode, method: MethodNode) {
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EncryptionMethod.FlattenedSwitch.transform(owner, method)
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}
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enum class EncryptionMethod {
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FlattenedSwitch {
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override fun transform(owner: ClassNode, method: MethodNode): Boolean {
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var transformed = false
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method.instructions.toList().forEach insn@{ insn ->
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if ((insn is LdcInsnNode && insn.cst is String)) {
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val (decrypt, newString) =
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generateDecryptMethod(
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insn.cst as String,
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owner,
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) ?: return@insn
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method.instructions.insertBefore(insn, insnList {
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LDC(newString)
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INVOKESTATIC(owner.name, decrypt.name, decrypt.desc)
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})
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method.instructions.remove(insn)
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transformed = true
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}
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}
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return transformed
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}
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private fun generateDecryptMethod(
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rawString: String,
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classNode: ClassNode
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): Pair<MethodNode, String>? {
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if (rawString.length <= 1) return null
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val keys = buildList { repeat(rawString.length) { add(Random.nextInt()) } }
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val encryptedString = buildString {
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rawString.forEachIndexed { i, c ->
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append((c.code xor keys[i]).toChar())
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}
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}
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require(encryptedString.length == rawString.length)
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val cases = rawString.indices.toList().shuffled()
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val casesMapping = mutableMapOf<Int, InsnList>()
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// here instancing LabelNode directly is soundness because we only use each node for one time.
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val labels = Array(cases.size) { LabelNode() }
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val decryptMethod = method(Opcodes.ACC_PUBLIC or Opcodes.ACC_STATIC,
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getRandomString(10), "(Ljava/lang/String;)Ljava/lang/String;") {
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var currentChar = 0
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var currentKey = keys[currentChar]
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val dispatchLabel = LabelNode()
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InsnList {
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// 0 -> encrypted string
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// 1 -> stringbuilder
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// 2 -> current char's decrypt key(transformed before decrypt in each switch case)
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// 3 -> program counter
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NEW("java/lang/StringBuilder")
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DUP
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INVOKESPECIAL("java/lang/StringBuilder", "<init>", "()V")
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ASTORE(1)
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LDC(keys[currentChar])
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ISTORE(2) // decrypt key
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LDC(cases[currentChar])
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ISTORE(3) // pc
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+dispatchLabel
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ILOAD(3)
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+TableSwitchInsnNode(0, rawString.length - 1, labels[cases.last()], *labels)
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}
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casesMapping[cases[currentChar]] = insnList {
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// the first case uses decrypt key directly
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+labels[cases[currentChar]]
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ALOAD(1) // builder
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ALOAD(0) // raw str
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require(currentChar == 0)
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LDC(currentChar)
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INVOKEVIRTUAL("java/lang/String", "charAt", "(I)C")
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ILOAD(2)
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IXOR
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INVOKEVIRTUAL("java/lang/StringBuilder",
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"append", "(C)Ljava/lang/StringBuilder;")
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POP
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currentChar++
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LDC(cases[currentChar])
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ISTORE(3) // pc
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GOTO(dispatchLabel)
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}
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while (currentChar < rawString.length - 1) {
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casesMapping[cases[currentChar]] = insnList {
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+labels[cases[currentChar]]
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LDC(keys[currentChar])
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ISTORE(2)
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currentKey = keys[currentChar]
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require(currentKey == keys[currentChar])
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ALOAD(1)
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ALOAD(0)
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LDC(currentChar)
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INVOKEVIRTUAL("java/lang/String", "charAt", "(I)C")
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ILOAD(2) // key
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IXOR
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INVOKEVIRTUAL("java/lang/StringBuilder",
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"append", "(C)Ljava/lang/StringBuilder;")
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POP
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currentChar++
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LDC(cases[currentChar])
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ISTORE(3) // pc
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GOTO(dispatchLabel)
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}
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}
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casesMapping.toList().sortedBy { it.first }.forEach { (_, insnList) ->
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+insnList
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}
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InsnList {
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+labels[cases.last()]
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LDC(keys.last())
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ISTORE(2)
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currentKey = keys.last()
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require(currentKey == keys.last())
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ALOAD(1)
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ALOAD(0)
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LDC(currentChar)
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INVOKEVIRTUAL("java/lang/String", "charAt", "(I)C")
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ILOAD(2)
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IXOR
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INVOKEVIRTUAL("java/lang/StringBuilder",
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"append", "(C)Ljava/lang/StringBuilder;")
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POP
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ALOAD(1)
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INVOKEVIRTUAL("java/lang/StringBuilder", "toString", "()Ljava/lang/String;")
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ARETURN
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}
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}
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classNode.methods.add(decryptMethod)
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return decryptMethod to encryptedString
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}
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};
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abstract fun transform(owner: ClassNode, method: MethodNode): Boolean
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}
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}

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