调整集合相关工具类。

src/main/java/xyz/zhouxy/plusone/commons/collection/MapTools.java

@@ -0,0 +1,17 @@
+package xyz.zhouxy.plusone.commons.collection;
+
+import java.util.Map;
+import java.util.function.Function;
+
+public class MapTools {
+
+    public static <K, V> void transformValue(Map<K, V> map, K key, Function<V, ? extends V> func) {
+        if (map.containsKey(key)) {
+            map.put(key, func.apply(map.get(key)));
+        }
+    }
+
+    private MapTools() {
+        throw new IllegalStateException("Utility class");
+    }
+}