Allow parsing of media types with single-quotes

Previously MediaType could only parse double-quoted parameters without
raising an IllegalArgumentException. Now parameters can also be
single-quoted.

Issue: SPR-8917

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

@@ -376,7 +376,12 @@ public class MediaType implements Comparable<MediaType> {
 	}
 
 	private boolean isQuotedString(String s) {
-		return s.length() > 1 && s.startsWith("\"") && s.endsWith("\"") ;
+		if (s.length() < 2) {
+			return false;
+		}
+		else {
+			return ((s.startsWith("\"") && s.endsWith("\"")) || (s.startsWith("'") && s.endsWith("'")));
+		}
 	}
 
 	private String unquote(String s) {

spring-web/src/test/java/org/springframework/http/MediaTypeTests.java

@@ -181,6 +181,14 @@ public class MediaTypeTests {
 		assertEquals("\"v>alue\"", mediaType.getParameter("attr"));
 	}
 
+	// SPR-8917
+
+	@Test
+	public void parseMediaTypeSingleQuotedParameterValue() {
+		MediaType mediaType = MediaType.parseMediaType("audio/*;attr='v>alue'");
+		assertEquals("'v>alue'", mediaType.getParameter("attr"));
+	}
+
 	@Test(expected = IllegalArgumentException.class)
 	public void parseMediaTypeIllegalQuotedParameterValue() {
 		MediaType.parseMediaType("audio/*;attr=\"");