Ensure consistent ButtonTag value attribute processing

Closes gh-37017

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/form/ButtonTag.java

@@ -67,6 +67,7 @@ import org.springframework.web.servlet.support.RequestDataValueProcessor;
  * </table>
  *
  * @author Rossen Stoyanchev
+ * @author Sebastien Deleuze
  * @since 3.1
  */
 @SuppressWarnings("serial")
@@ -152,7 +153,8 @@ public class ButtonTag extends AbstractHtmlElementTag {
 	 */
 	protected void writeValue(TagWriter tagWriter) throws JspException {
 		String valueToUse = (getValue() != null ? getValue() : getDefaultValue());
-		tagWriter.writeAttribute("value", processFieldValue(getName(), valueToUse, getType()));
+		tagWriter.writeAttribute("value",
+				processFieldValue(getName(), getDisplayString(valueToUse), getType()));
 	}
 
 	/**

spring-webmvc/src/test/java/org/springframework/web/servlet/tags/form/ButtonTagTests.java

@@ -27,6 +27,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Rossen Stoyanchev
+ * @author Sebastien Deleuze
  */
 class ButtonTagTests extends AbstractFormTagTests {
 
@@ -58,6 +59,20 @@ class ButtonTagTests extends AbstractFormTagTests {
 		assertAttributeNotPresent(output, "disabled");
 	}
 
+	@Test
+	void value() throws Exception {
+		this.tag.setValue("\"My Button\"");
+
+		assertThat(this.tag.doStartTag()).isEqualTo(Tag.EVAL_BODY_INCLUDE);
+		assertThat(this.tag.doEndTag()).isEqualTo(Tag.EVAL_PAGE);
+
+		String output = getOutput();
+		assertTagOpened(output);
+		assertTagClosed(output);
+
+		assertContainsAttribute(output, "value", ""My Button"");
+	}
+
 	@Test
 	void disabled() throws Exception {
 		this.tag.setDisabled(true);