From 6495a50df74e0179e9548b0462aeb87ee40461aa Mon Sep 17 00:00:00 2001
From: Mark Paluch <mpaluch@pivotal.io>
Date: Tue, 27 Jun 2017 18:27:15 +0200
Subject: [PATCH] DATACMNS-1101 - Replace ArrayList indirections in
 ReflectionEntityInstantiator/PreferredConstructor.

Iterate over simple ArrayList and construct array of params instead of copying elements between multiple Lists.
---
 .../convert/ReflectionEntityInstantiator.java    | 16 +++++++---------
 .../data/mapping/PreferredConstructor.java       |  5 ++---
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/src/main/java/org/springframework/data/convert/ReflectionEntityInstantiator.java b/src/main/java/org/springframework/data/convert/ReflectionEntityInstantiator.java
index 5ed93267c..df27287d3 100644
--- a/src/main/java/org/springframework/data/convert/ReflectionEntityInstantiator.java
+++ b/src/main/java/org/springframework/data/convert/ReflectionEntityInstantiator.java
@@ -16,9 +16,8 @@
 package org.springframework.data.convert;
 
 import java.lang.reflect.Array;
-import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
-import java.util.List;
 
 import org.springframework.beans.BeanInstantiationException;
 import org.springframework.beans.BeanUtils;
@@ -66,17 +65,16 @@ public enum ReflectionEntityInstantiator implements EntityInstantiator {
 			}
 		}
 
-		List<Object> params = new ArrayList<>();
-		if (null != provider && constructor.hasParameters()) {
-			for (Parameter<?, P> parameter : constructor.getParameters()) {
-				params.add(provider.getParameterValue(parameter));
-			}
+		Object[] params = new Object[constructor.getConstructor().getParameterCount()];
+		int i = 0;
+		for (Parameter<?, P> parameter : constructor.getParameters()) {
+			params[i++] = provider.getParameterValue(parameter);
 		}
 
 		try {
-			return BeanUtils.instantiateClass(constructor.getConstructor(), params.toArray());
+			return BeanUtils.instantiateClass(constructor.getConstructor(), params);
 		} catch (BeanInstantiationException e) {
-			throw new MappingInstantiationException(entity, params, e);
+			throw new MappingInstantiationException(entity, Arrays.asList(params), e);
 		}
 	}
 }
diff --git a/src/main/java/org/springframework/data/mapping/PreferredConstructor.java b/src/main/java/org/springframework/data/mapping/PreferredConstructor.java
index e9c4587ea..e1d5eee72 100644
--- a/src/main/java/org/springframework/data/mapping/PreferredConstructor.java
+++ b/src/main/java/org/springframework/data/mapping/PreferredConstructor.java
@@ -29,7 +29,6 @@ import java.util.concurrent.locks.ReentrantReadWriteLock;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.data.annotation.PersistenceConstructor;
 import org.springframework.data.util.Lazy;
-import org.springframework.data.util.Streamable;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
@@ -85,8 +84,8 @@ public class PreferredConstructor<T, P extends PersistentProperty<P>> {
 	 *
 	 * @return
 	 */
-	public Streamable<Parameter<Object, P>> getParameters() {
-		return Streamable.of(parameters);
+	public List<Parameter<Object, P>> getParameters() {
+		return parameters;
 	}
 
 	/**