From 93ea2e1df95eeb00f2475c7a5360c4a293a490ab Mon Sep 17 00:00:00 2001
From: rstoyanchev <rstoyanchev@vmware.com>
Date: Mon, 5 Dec 2022 15:22:37 +0000
Subject: [PATCH] Push canWrite down into MultipartHttpMessageWriter

The implementation in the base class only matches the
MultipartHttpMessageWriter subclass. The other two override it anyway.

Closes gh-29631
---
 .../multipart/MultipartHttpMessageWriter.java   | 14 ++++++++++++++
 .../codec/multipart/MultipartWriterSupport.java | 17 -----------------
 .../multipart/PartHttpMessageWriterTests.java   |  1 +
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartHttpMessageWriter.java b/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartHttpMessageWriter.java
index 4eced82403d3..777b5991ab86 100644
--- a/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartHttpMessageWriter.java
+++ b/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartHttpMessageWriter.java
@@ -145,6 +145,20 @@ public HttpMessageWriter<MultiValueMap<String, String>> getFormWriter() {
 	}
 
 
+	@Override
+	public boolean canWrite(ResolvableType elementType, @Nullable MediaType mediaType) {
+		if (MultiValueMap.class.isAssignableFrom(elementType.toClass())) {
+			if (mediaType == null) {
+				return true;
+			}
+			for (MediaType supportedMediaType : getWritableMediaTypes()) {
+				if (supportedMediaType.isCompatibleWith(mediaType)) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
 
 	@Override
 	public Mono<Void> write(Publisher<? extends MultiValueMap<String, ?>> inputStream,
diff --git a/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartWriterSupport.java b/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartWriterSupport.java
index 0bd3bfa23069..9e78ab9a9e9b 100644
--- a/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartWriterSupport.java
+++ b/spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartWriterSupport.java
@@ -24,7 +24,6 @@
 
 import reactor.core.publisher.Mono;
 
-import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.http.HttpHeaders;
@@ -34,7 +33,6 @@
 import org.springframework.util.Assert;
 import org.springframework.util.FastByteArrayOutputStream;
 import org.springframework.util.MimeTypeUtils;
-import org.springframework.util.MultiValueMap;
 
 /**
  * Support class for multipart HTTP message writers.
@@ -83,21 +81,6 @@ public List<MediaType> getWritableMediaTypes() {
 		return this.supportedMediaTypes;
 	}
 
-
-	public boolean canWrite(ResolvableType elementType, @Nullable MediaType mediaType) {
-		if (MultiValueMap.class.isAssignableFrom(elementType.toClass())) {
-			if (mediaType == null) {
-				return true;
-			}
-			for (MediaType supportedMediaType : this.supportedMediaTypes) {
-				if (supportedMediaType.isCompatibleWith(mediaType)) {
-					return true;
-				}
-			}
-		}
-		return false;
-	}
-
 	/**
 	 * Generate a multipart boundary.
 	 * <p>By default delegates to {@link MimeTypeUtils#generateMultipartBoundary()}.
diff --git a/spring-web/src/test/java/org/springframework/http/codec/multipart/PartHttpMessageWriterTests.java b/spring-web/src/test/java/org/springframework/http/codec/multipart/PartHttpMessageWriterTests.java
index 1b46417aa895..b9f452a27b78 100644
--- a/spring-web/src/test/java/org/springframework/http/codec/multipart/PartHttpMessageWriterTests.java
+++ b/spring-web/src/test/java/org/springframework/http/codec/multipart/PartHttpMessageWriterTests.java
@@ -55,6 +55,7 @@ public void canWrite() {
 		assertThat(this.writer.canWrite(ResolvableType.forClass(Part.class), MediaType.MULTIPART_FORM_DATA)).isTrue();
 		assertThat(this.writer.canWrite(ResolvableType.forClass(Part.class), MediaType.MULTIPART_MIXED)).isTrue();
 		assertThat(this.writer.canWrite(ResolvableType.forClass(Part.class), MediaType.MULTIPART_RELATED)).isTrue();
+		assertThat(this.writer.canWrite(ResolvableType.forClass(MultiValueMap.class), MediaType.MULTIPART_FORM_DATA)).isFalse();
 	}
 
 	@Test