Lenient handling of empty Content-Disposition filename

Closes gh-25769

Author: jhoeller

spring-web/src/main/java/org/springframework/http/HttpHeaders.java

@@ -861,7 +861,7 @@ public List<String> getConnection() {
 	public void setContentDispositionFormData(String name, @Nullable String filename) {
 		Assert.notNull(name, "Name must not be null");
 		ContentDisposition.Builder disposition = ContentDisposition.builder("form-data").name(name);
-		if (filename != null) {
+		if (StringUtils.hasText(filename)) {
 			disposition.filename(filename);
 		}
 		setContentDisposition(disposition.build());
@@ -888,7 +888,7 @@ public void setContentDisposition(ContentDisposition contentDisposition) {
 	 */
 	public ContentDisposition getContentDisposition() {
 		String contentDisposition = getFirst(CONTENT_DISPOSITION);
-		if (contentDisposition != null) {
+		if (StringUtils.hasText(contentDisposition)) {
 			return ContentDisposition.parse(contentDisposition);
 		}
 		return ContentDisposition.empty();