Restore base class of MissingServletRequestPartException

Effectively reverts commit #ad2722.

Closes gh-28455

spring-web/src/main/java/org/springframework/web/ErrorResponse.java

@@ -29,14 +29,14 @@ import org.springframework.http.ProblemDetail;
  * <p>{@link ErrorResponseException} is a default implementation of this
  * interface and a convenient base class for other exceptions to use.
  *
- * <p>An {@code @ExceptionHandler} method can use
- * {@link org.springframework.http.ResponseEntity#of(ErrorResponse)} to map an
- * {@code ErrorResponse} to a {@code ResponseEntity}.
+ * <p>{@code ErrorResponse} is supported as a return value from
+ * {@code @ExceptionHandler} methods that render directly to the response, e.g.
+ * by being marked {@code @ResponseBody}, or declared in an
+ * {@code @RestController} or {@code RestControllerAdvice} class.
  *
  * @author Rossen Stoyanchev
  * @since 6.0
  * @see ErrorResponseException
- * @see org.springframework.http.ResponseEntity#of(ErrorResponse)
  */
 public interface ErrorResponse {
 

spring-web/src/main/java/org/springframework/web/multipart/support/MissingServletRequestPartException.java

@@ -16,7 +16,12 @@
 
 package org.springframework.web.multipart.support;
 
-import org.springframework.web.bind.ServletRequestBindingException;
+import jakarta.servlet.ServletException;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.HttpStatusCode;
+import org.springframework.http.ProblemDetail;
+import org.springframework.web.ErrorResponse;
 import org.springframework.web.multipart.MultipartResolver;
 
 /**
@@ -26,14 +31,22 @@ import org.springframework.web.multipart.MultipartResolver;
  * is not configured correctly for processing multipart requests, e.g. there
  * is no {@link MultipartResolver}.
  *
+ * <p><strong>Note:</strong> This exception does not extend from
+ * {@link org.springframework.web.bind.ServletRequestBindingException} because
+ * it can also be raised at a lower level, i.e. from this package which does
+ * low level multipart request parsing, independent of higher level request
+ * binding features.
+ *
  * @author Rossen Stoyanchev
  * @since 3.1
  */
 @SuppressWarnings("serial")
-public class MissingServletRequestPartException extends ServletRequestBindingException {
+public class MissingServletRequestPartException extends ServletException implements ErrorResponse {
 
 	private final String requestPartName;
 
+	private final ProblemDetail body = ProblemDetail.forStatus(getStatusCode());
+
 
 	/**
 	 * Constructor for MissingServletRequestPartException.
@@ -53,4 +66,22 @@ public class MissingServletRequestPartException extends ServletRequestBindingExc
 		return this.requestPartName;
 	}
 
+	/**
+	 * Return the HTTP status code to use for the response.
+	 */
+	@Override
+	public HttpStatusCode getStatusCode() {
+		return HttpStatus.BAD_REQUEST;
+	}
+
+	/**
+	 * Return the body for the response, formatted as an RFC 7807
+	 * {@link ProblemDetail} whose {@link ProblemDetail#getStatus() status}
+	 * should match the response status.
+	 */
+	@Override
+	public ProblemDetail getBody() {
+		return this.body;
+	}
+
 }