diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/handler/PacketHandler.kt b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/handler/PacketHandler.kt
index 8c3db56d5..1e2b98100 100644
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/handler/PacketHandler.kt
+++ b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/handler/PacketHandler.kt
@@ -2,7 +2,6 @@ package net.mamoe.mirai.network.protocol.tim.handler
 
 import net.mamoe.mirai.network.LoginSession
 import net.mamoe.mirai.network.protocol.tim.packet.ServerPacket
-import net.mamoe.mirai.utils.MiraiSynchronizedLinkedList
 import java.io.Closeable
 
 /**
@@ -27,7 +26,7 @@ fun PacketHandler.asNode(): PacketHandlerNode<PacketHandler> {
     return PacketHandlerNode(this.javaClass, this)
 }
 
-class PacketHandlerList : MiraiSynchronizedLinkedList<PacketHandlerNode<*>>() {
+class PacketHandlerList : MutableList<PacketHandlerNode<*>> by mutableListOf() {
 
     fun <T : PacketHandler> get(clazz: Class<T>): T {
         this.forEach {
diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/packet/PacketId.kt b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/packet/PacketId.kt
index c53cad733..8ede36192 100644
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/packet/PacketId.kt
+++ b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/network/protocol/tim/packet/PacketId.kt
@@ -1,18 +1,13 @@
-package net.mamoe.mirai.network.protocol.tim.packet;
-
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
+package net.mamoe.mirai.network.protocol.tim.packet
 
 /**
  * @author Him188moe
  */
-@Retention(RetentionPolicy.RUNTIME)
-@Target(ElementType.TYPE)
-public @interface PacketId {
-    /**
-     * 获取用于识别的包 ID
-     */
-    String value();
-}
+@Retention(AnnotationRetention.RUNTIME)
+@Target(AnnotationTarget.CLASS, AnnotationTarget.FILE)
+annotation class PacketId(
+        /**
+         * 用于识别的包 ID
+         */
+        val value: String
+)
diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/ContactList.kt b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/ContactList.kt
index b4df58a6a..3332e0bfb 100644
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/ContactList.kt
+++ b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/ContactList.kt
@@ -5,4 +5,4 @@ import net.mamoe.mirai.contact.Contact
 /**
  * @author Him188moe
  */
-class ContactList<C : Contact> : MiraiSynchronizedLinkedHashMap<Long, C>()
\ No newline at end of file
+class ContactList<C : Contact> : MutableMap<Long, C> by mutableMapOf()
\ No newline at end of file
diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/MiraiSynchronizedLinkedHashMap.java b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/MiraiSynchronizedLinkedHashMap.java
deleted file mode 100644
index 6c5795f84..000000000
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/MiraiSynchronizedLinkedHashMap.java
+++ /dev/null
@@ -1,158 +0,0 @@
-package net.mamoe.mirai.utils;
-
-import java.util.*;
-import java.util.function.BiConsumer;
-import java.util.function.BiFunction;
-import java.util.function.Function;
-
-/**
- * 实现了可以直接被继承的 SynchronizedLinkedListMap<K,V>
- *
- * @param <K> the type of key
- * @param <V> the type of value
- *
- * @author NaturalHG
- */
-public class MiraiSynchronizedLinkedHashMap<K, V> extends AbstractMap<K, V> {
-
-    public MiraiSynchronizedLinkedHashMap() {
-        this.sortedMap = Collections.synchronizedMap(new LinkedHashMap<>());
-    }
-
-    protected final Map<K, V> sortedMap;
-
-    public MiraiSynchronizedLinkedHashMap(LinkedHashMap<K, V> map) {
-        this.sortedMap = Collections.synchronizedMap(map);
-    }
-
-
-    @Override
-    public int size() {
-        return sortedMap.size();
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return sortedMap.isEmpty();
-    }
-
-    @Override
-    public boolean containsKey(Object key) {
-        return sortedMap.containsKey(key);
-    }
-
-    @Override
-    public boolean containsValue(Object value) {
-        return sortedMap.containsValue(value);
-    }
-
-    @Override
-    public V get(Object key) {
-        return sortedMap.get(key);
-    }
-
-    @Override
-    public V put(K key, V value) {
-        return sortedMap.put(key,value);
-    }
-
-    @Override
-    public V remove(Object key) {
-        return sortedMap.remove(key);
-    }
-
-    @Override
-    public void putAll(Map<? extends K, ? extends V> m) {
-        sortedMap.putAll(m);
-    }
-
-    @Override
-    public void clear() {
-        sortedMap.clear();
-    }
-
-    @Override
-    public Set<K> keySet() {
-        return sortedMap.keySet();
-    }
-
-    @Override
-    public Collection<V> values() {
-        return sortedMap.values();
-    }
-
-    @Override
-    public Set<Entry<K, V>> entrySet() {
-        return sortedMap.entrySet();
-    }
-
-    @Override
-    public String toString() {
-        return this.sortedMap.toString();
-    }
-
-    @Override
-    public V getOrDefault(Object key, V defaultValue) {
-        return this.sortedMap.getOrDefault(key,defaultValue);
-    }
-
-    @Override
-    public void forEach(BiConsumer<? super K, ? super V> action) {
-        this.sortedMap.forEach(action);
-    }
-
-    @Override
-    public boolean replace(K key, V oldValue, V newValue) {
-        return this.sortedMap.replace(key,oldValue,newValue);
-    }
-
-    @Override
-    public V replace(K key, V value) {
-        return this.sortedMap.replace(key,value);
-    }
-
-    @Override
-    public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
-        this.sortedMap.replaceAll(function);
-    }
-
-    @Override
-    public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
-        return this.sortedMap.compute(key,remappingFunction);
-    }
-
-    @Override
-    public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
-        return this.sortedMap.computeIfAbsent(key,mappingFunction);
-    }
-
-    @Override
-    public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
-        return this.sortedMap.computeIfPresent(key,remappingFunction);
-    }
-
-    @Override
-    public int hashCode() {
-        return this.sortedMap.hashCode();
-    }
-
-    @Override
-    public V putIfAbsent(K key, V value) {
-        return this.sortedMap.putIfAbsent(key,value);
-    }
-
-    @Override
-    public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
-        return this.sortedMap.merge(key,value,remappingFunction);
-    }
-
-    public boolean equals(MiraiSynchronizedLinkedHashMap o) {
-        return this.sortedMap.equals(o.sortedMap);
-    }
-
-    @Override
-    public boolean equals(Object o) {
-        return o instanceof MiraiSynchronizedLinkedHashMap ? this.equals((MiraiSynchronizedLinkedHashMap) o) : super.equals(o);
-    }
-
-}
diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/MiraiSynchronizedLinkedList.java b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/MiraiSynchronizedLinkedList.java
deleted file mode 100644
index 10691f929..000000000
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/MiraiSynchronizedLinkedList.java
+++ /dev/null
@@ -1,187 +0,0 @@
-package net.mamoe.mirai.utils;
-
-import java.util.*;
-import java.util.function.Consumer;
-import java.util.function.IntFunction;
-import java.util.function.Predicate;
-import java.util.function.UnaryOperator;
-import java.util.stream.Stream;
-
-/**
- * @author Him188moe
- */
-public class MiraiSynchronizedLinkedList<E> extends AbstractList<E> {
-    @SuppressWarnings("WeakerAccess")
-    protected final List<E> syncList;
-
-    public MiraiSynchronizedLinkedList() {
-        this.syncList = Collections.synchronizedList(new LinkedList<>());
-    }
-
-    public MiraiSynchronizedLinkedList(Collection<E> collection) {
-        this.syncList = Collections.synchronizedList(new LinkedList<>(collection));
-    }
-
-
-    @Override
-    public E get(int index) {
-        return this.syncList.get(index);
-    }
-
-    @Override
-    public void forEach(Consumer<? super E> action) {
-        this.syncList.forEach(action);
-    }
-
-    @Override
-    public Spliterator<E> spliterator() {
-        return this.syncList.spliterator();
-    }
-
-    @Override
-    public Stream<E> stream() {
-        return this.syncList.stream();
-    }
-
-    @Override
-    public Stream<E> parallelStream() {
-        return this.syncList.parallelStream();
-    }
-
-    @Override
-    public int size() {
-        return this.syncList.size();
-    }
-
-    @SuppressWarnings("SuspiciousToArrayCall")
-    @Override
-    public <T> T[] toArray(IntFunction<T[]> generator) {
-        return this.syncList.toArray(generator);
-    }
-
-    @Override
-    public boolean removeIf(Predicate<? super E> filter) {
-        return this.syncList.removeIf(filter);
-    }
-
-    @Override
-    public void replaceAll(UnaryOperator<E> operator) {
-        this.syncList.replaceAll(operator);
-    }
-
-    @Override
-    public void sort(Comparator<? super E> c) {
-        this.syncList.sort(c);
-    }
-
-    @Override
-    public boolean add(E e) {
-        return this.syncList.add(e);
-    }
-
-    @Override
-    public E set(int index, E element) {
-        return this.syncList.set(index, element);
-    }
-
-    @Override
-    public void add(int index, E element) {
-        this.syncList.add(index, element);
-    }
-
-    @Override
-    public E remove(int index) {
-        return this.syncList.remove(index);
-    }
-
-    @Override
-    public int indexOf(Object o) {
-        return this.syncList.indexOf(o);
-    }
-
-    @Override
-    public int lastIndexOf(Object o) {
-        return this.syncList.lastIndexOf(o);
-    }
-
-    @Override
-    public void clear() {
-        this.syncList.clear();
-    }
-
-    @Override
-    public boolean addAll(int index, Collection<? extends E> c) {
-        return this.syncList.addAll(index, c);
-    }
-
-    @Override
-    public Iterator<E> iterator() {
-        return this.syncList.iterator();
-    }
-
-    @Override
-    public ListIterator<E> listIterator() {
-        return this.syncList.listIterator();
-    }
-
-    @Override
-    public ListIterator<E> listIterator(int index) {
-        return this.syncList.listIterator(index);
-    }
-
-    @Override
-    public List<E> subList(int fromIndex, int toIndex) {
-        return this.syncList.subList(fromIndex, toIndex);
-    }
-
-    @Override
-    public int hashCode() {
-        return this.syncList.hashCode();
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return this.syncList.isEmpty();
-    }
-
-    @Override
-    public boolean contains(Object o) {
-        return this.syncList.contains(o);
-    }
-
-    @Override
-    public Object[] toArray() {
-        return this.syncList.toArray();
-    }
-
-    @SuppressWarnings("SuspiciousToArrayCall")
-    @Override
-    public <T> T[] toArray(T[] a) {
-        return this.syncList.toArray(a);
-    }
-
-    @Override
-    public boolean remove(Object o) {
-        return this.syncList.remove(o);
-    }
-
-    @Override
-    public boolean containsAll(Collection<?> c) {
-        return this.syncList.containsAll(c);
-    }
-
-    @Override
-    public boolean addAll(Collection<? extends E> c) {
-        return this.syncList.addAll(c);
-    }
-
-    @Override
-    public boolean removeAll(Collection<?> c) {
-        return this.syncList.removeAll(c);
-    }
-
-    @Override
-    public boolean retainAll(Collection<?> c) {
-        return this.syncList.retainAll(c);
-    }
-}
diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfig.kt b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfig.kt
index aa8062ee3..5e9cf3171 100644
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfig.kt
+++ b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfig.kt
@@ -22,7 +22,7 @@ class MiraiConfig(private val root: File) : MiraiConfigSection<Any>(parse(Object
         val dumperOptions = DumperOptions()
         dumperOptions.defaultFlowStyle = DumperOptions.FlowStyle.BLOCK
         val yaml = Yaml(dumperOptions)
-        val content = yaml.dump(this.sortedMap)
+        val content = yaml.dump(this)
         try {
             ByteArrayInputStream(content.toByteArray()).transferTo(FileOutputStream(this.root))
         } catch (e: IOException) {
diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfigSection.java b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfigSection.java
index 10a83d414..1e1236c5b 100644
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfigSection.java
+++ b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/utils/config/MiraiConfigSection.java
@@ -1,7 +1,5 @@
 package net.mamoe.mirai.utils.config;
 
-import net.mamoe.mirai.utils.MiraiSynchronizedLinkedHashMap;
-
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.concurrent.Callable;
@@ -10,7 +8,7 @@ import java.util.function.Supplier;
 /**
  * @author NaturalHG
  */
-public class MiraiConfigSection<T> extends MiraiSynchronizedLinkedHashMap<String, T> {
+public class MiraiConfigSection<T> extends LinkedHashMap<String, T> {
 
     public MiraiConfigSection(){
         super();