[hotfix][client] Use more efficient EnumMap (#1882)

Author: snuyanzin

fluss-client/src/main/java/org/apache/fluss/client/converter/ConverterCommons.java

@@ -24,7 +24,7 @@
 
 import java.math.BigDecimal;
 import java.util.Arrays;
-import java.util.HashMap;
+import java.util.EnumMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
@@ -43,7 +43,7 @@ final class ConverterCommons {
     static final Map<DataTypeRoot, Set<Class<?>>> SUPPORTED_TYPES = createSupportedTypes();
 
     private static Map<DataTypeRoot, Set<Class<?>>> createSupportedTypes() {
-        Map<DataTypeRoot, Set<Class<?>>> map = new HashMap<>();
+        Map<DataTypeRoot, Set<Class<?>>> map = new EnumMap<>(DataTypeRoot.class);
         map.put(DataTypeRoot.BOOLEAN, setOf(Boolean.class));
         map.put(DataTypeRoot.TINYINT, setOf(Byte.class));
         map.put(DataTypeRoot.SMALLINT, setOf(Short.class));