SPR-8697 Flag '*/subtype' as illegal.

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

@@ -575,6 +575,9 @@ public class MediaType implements Comparable<MediaType> {
 		}
 		String type = fullType.substring(0, subIndex);
 		String subtype = fullType.substring(subIndex + 1, fullType.length());
+		if (WILDCARD_TYPE.equals(type) && !WILDCARD_TYPE.equals(subtype)) {
+			throw new IllegalArgumentException("A wildcard type is legal only in '*/*' (all media types).");
+		}
 
 		Map<String, String> parameters = null;
 		if (parts.length > 1) {

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

@@ -128,6 +128,11 @@ public class MediaTypeTests {
 		MediaType.parseMediaType("audio/");
 	}
 
+	@Test(expected = IllegalArgumentException.class)
+	public void parseMediaTypeTypeRange() {
+		MediaType.parseMediaType("*/json");
+	}
+
 	@Test(expected = IllegalArgumentException.class)
 	public void parseMediaTypeIllegalType() {
 		MediaType.parseMediaType("audio(/basic");