deserialize support EnumMap, for issue alibaba#1679

core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderImplMap.java

@@ -169,6 +169,9 @@ public static ObjectReader of(Type fieldType, Class mapType, long features) {
                         Map.Entry entry = (Map.Entry) map.entrySet().iterator().next();
                         return Collections.singletonMap(entry.getKey(), entry.getValue());
                     };
+                } else if (mapType == EnumMap.class) {
+                    instanceType = LinkedHashMap.class;
+                    builder = e -> new EnumMap((Map) e);
                 }
         }
 

core/src/test/java/com/alibaba/fastjson2/issues_1600/Issue1679.java

@@ -0,0 +1,26 @@
+package com.alibaba.fastjson2.issues_1600;
+
+import com.alibaba.fastjson2.JSONB;
+import com.alibaba.fastjson2.JSONReader;
+import com.alibaba.fastjson2.JSONWriter;
+import org.junit.jupiter.api.Test;
+
+import java.util.EnumMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class Issue1679 {
+    @Test
+    public void test() {
+        Map<TimeUnit, String> map = new LinkedHashMap<>();
+        map.put(TimeUnit.DAYS, "day");
+        EnumMap<TimeUnit, String> enumMap = new EnumMap(map);
+
+        byte[] jsonbBytes = JSONB.toBytes(enumMap, JSONWriter.Feature.WriteClassName);
+        EnumMap enumMap1 = JSONB.parseObject(jsonbBytes, EnumMap.class, JSONReader.Feature.SupportAutoType);
+        assertEquals(enumMap.get(TimeUnit.DAYS), enumMap1.get(TimeUnit.DAYS));
+    }
+}