Jackson decoder supports array/Collection elements

Closes gh-32579

Author: rstoyanchev

spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Decoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.lang.annotation.Annotation;
 import java.math.BigDecimal;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
@@ -135,9 +136,12 @@ public Flux<Object> decode(Publisher<DataBuffer> input, ResolvableType elementTy
 			forceUseOfBigDecimal = true;
 		}
 
+		boolean tokenizeArrays = (!elementType.isArray() &&
+				!Collection.class.isAssignableFrom(elementType.resolve(Object.class)));
+
 		Flux<DataBuffer> processed = processInput(input, elementType, mimeType, hints);
 		Flux<TokenBuffer> tokens = Jackson2Tokenizer.tokenize(processed, mapper.getFactory(), mapper,
-				true, forceUseOfBigDecimal, getMaxInMemorySize());
+				tokenizeArrays, forceUseOfBigDecimal, getMaxInMemorySize());
 
 		return Flux.deferContextual(contextView -> {
 

spring-web/src/test/java/org/springframework/http/codec/json/Jackson2JsonDecoderTests.java

@@ -46,6 +46,7 @@
 import org.springframework.http.codec.json.JacksonViewBean.MyJacksonView1;
 import org.springframework.http.codec.json.JacksonViewBean.MyJacksonView3;
 import org.springframework.util.MimeType;
+import org.springframework.util.MimeTypeUtils;
 import org.springframework.web.testfixture.xml.Pojo;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -172,6 +173,22 @@ protected void decodeToMono() {
 				.verify(), null, null);
 	}
 
+	@Test
+	protected void decodeToFluxWithListElements() {
+		Flux<DataBuffer> input = Flux.concat(
+				stringBuffer("[{\"bar\":\"b1\",\"foo\":\"f1\"},{\"bar\":\"b2\",\"foo\":\"f2\"}]"),
+				stringBuffer("[{\"bar\":\"b3\",\"foo\":\"f3\"},{\"bar\":\"b4\",\"foo\":\"f4\"}]"));
+
+		ResolvableType elementType = ResolvableType.forClassWithGenerics(List.class, Pojo.class);
+
+		testDecodeAll(input, elementType,
+				step -> step
+						.expectNext(List.of(pojo1, pojo2))
+						.expectNext(List.of(new Pojo("f3", "b3"), new Pojo("f4", "b4")))
+						.verifyComplete(),
+				MimeTypeUtils.APPLICATION_JSON,
+				Collections.emptyMap());
+	}
 
 	@Test
 	void decodeEmptyArrayToFlux() {