From f88c314e834d5d5150d1ee444b0a8d96608b1309 Mon Sep 17 00:00:00 2001
From: Patrick Strawderman <pstrawderman@netflix.com>
Date: Tue, 3 Sep 2024 23:34:19 -0700
Subject: [PATCH] Avoid empty array allocations in ResolvableType

Avoid allocating empty arrays in a few places in ResolvableType.

Closes gh-33473
---
 .../springframework/core/ResolvableType.java  | 33 ++++++++++++++-----
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/spring-core/src/main/java/org/springframework/core/ResolvableType.java b/spring-core/src/main/java/org/springframework/core/ResolvableType.java
index ed541ebbda63..bc76795032eb 100644
--- a/spring-core/src/main/java/org/springframework/core/ResolvableType.java
+++ b/spring-core/src/main/java/org/springframework/core/ResolvableType.java
@@ -549,9 +549,14 @@ public ResolvableType[] getInterfaces() {
 		ResolvableType[] interfaces = this.interfaces;
 		if (interfaces == null) {
 			Type[] genericIfcs = resolved.getGenericInterfaces();
-			interfaces = new ResolvableType[genericIfcs.length];
-			for (int i = 0; i < genericIfcs.length; i++) {
-				interfaces[i] = forType(genericIfcs[i], this);
+			if (genericIfcs.length > 0) {
+				interfaces = new ResolvableType[genericIfcs.length];
+				for (int i = 0; i < genericIfcs.length; i++) {
+					interfaces[i] = forType(genericIfcs[i], this);
+				}
+			}
+			else {
+				interfaces = EMPTY_TYPES_ARRAY;
 			}
 			this.interfaces = interfaces;
 		}
@@ -789,16 +794,26 @@ public ResolvableType[] getGenerics() {
 		if (generics == null) {
 			if (this.type instanceof Class<?> clazz) {
 				Type[] typeParams = clazz.getTypeParameters();
-				generics = new ResolvableType[typeParams.length];
-				for (int i = 0; i < generics.length; i++) {
-					generics[i] = ResolvableType.forType(typeParams[i], this);
+				if (typeParams.length > 0) {
+					generics = new ResolvableType[typeParams.length];
+					for (int i = 0; i < generics.length; i++) {
+						generics[i] = ResolvableType.forType(typeParams[i], this);
+					}
+				}
+				else {
+					generics = EMPTY_TYPES_ARRAY;
 				}
 			}
 			else if (this.type instanceof ParameterizedType parameterizedType) {
 				Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
-				generics = new ResolvableType[actualTypeArguments.length];
-				for (int i = 0; i < actualTypeArguments.length; i++) {
-					generics[i] = forType(actualTypeArguments[i], this.variableResolver);
+				if (actualTypeArguments.length > 0) {
+					generics = new ResolvableType[actualTypeArguments.length];
+					for (int i = 0; i < actualTypeArguments.length; i++) {
+						generics[i] = forType(actualTypeArguments[i], this.variableResolver);
+					}
+				}
+				else {
+					generics = EMPTY_TYPES_ARRAY;
 				}
 			}
 			else {