From 1afc1fc90d4f4b6df80c5aa384c2a47e01da6345 Mon Sep 17 00:00:00 2001
From: rstoyanchev <rstoyanchev@vmware.com>
Date: Fri, 7 Oct 2022 18:05:35 +0100
Subject: [PATCH] Fix regression in AbstractJackson2Encoder

Closes gh-29274
---
 .../http/codec/json/AbstractJackson2Encoder.java          | 1 +
 .../http/codec/json/Jackson2JsonEncoderTests.java         | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Encoder.java b/spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Encoder.java
index dd1ce11ee70..21c55e4fc71 100644
--- a/spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Encoder.java
+++ b/spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Encoder.java
@@ -198,6 +198,7 @@ public abstract class AbstractJackson2Encoder extends Jackson2CodecSupport imple
 										bufferFactory.join(Arrays.asList(bufferFactory.wrap(prefix), dataBuffer)) :
 										dataBuffer);
 							})
+							.switchIfEmpty(Mono.fromCallable(() -> bufferFactory.wrap(helper.getPrefix())))
 							.concatWith(Mono.fromCallable(() -> bufferFactory.wrap(helper.getSuffix())));
 				}
 
diff --git a/spring-web/src/test/java/org/springframework/http/codec/json/Jackson2JsonEncoderTests.java b/spring-web/src/test/java/org/springframework/http/codec/json/Jackson2JsonEncoderTests.java
index 786be589527..dbdca0ea99a 100644
--- a/spring-web/src/test/java/org/springframework/http/codec/json/Jackson2JsonEncoderTests.java
+++ b/spring-web/src/test/java/org/springframework/http/codec/json/Jackson2JsonEncoderTests.java
@@ -144,6 +144,14 @@ public class Jackson2JsonEncoderTests extends AbstractEncoderTests<Jackson2JsonE
 				.verifyComplete());
 	}
 
+	@Test
+	public void encodeNonStreamEmpty() {
+		testEncode(Flux.empty(), Pojo.class, step -> step
+				.consumeNextWith(expectString("["))
+				.consumeNextWith(expectString("]"))
+				.verifyComplete());
+	}
+
 	@Test // gh-29038
 	void encodeNonStreamWithErrorAsFirstSignal() {
 		String message = "I'm a teapot";