[hotfix] Improve performance of GenericArraySerializer.copy()

flink-core/src/main/java/org/apache/flink/api/common/typeutils/base/GenericArraySerializer.java

@@ -25,6 +25,7 @@
 
 import java.io.IOException;
 import java.lang.reflect.Array;
+import java.util.Arrays;
 
 import static org.apache.flink.util.Preconditions.checkNotNull;
 
@@ -86,16 +87,21 @@ public C[] createInstance() {
 
 	@Override
 	public C[] copy(C[] from) {
-		C[] copy = create(from.length);
 
-		for (int i = 0; i < copy.length; i++) {
-			C val = from[i];
-			if (val != null) {
-				copy[i] = this.componentSerializer.copy(val);
+		final TypeSerializer<C> serializer = this.componentSerializer;
+
+		if (serializer.isImmutableType()) {
+			return Arrays.copyOf(from, from.length);
+		} else {
+			C[] copy = create(from.length);
+			for (int i = 0; i < copy.length; i++) {
+				C val = from[i];
+				if (val != null) {
+					copy[i] = serializer.copy(val);
+				}
 			}
+			return copy;
 		}
-
-		return copy;
 	}
 
 	@Override