Pruning of outdated JDK 6/7 references (plus related polishing)

(cherry picked from commit b325c74216)

spring-core/src/main/java/org/springframework/core/annotation/OrderUtils.java

@@ -49,7 +49,7 @@ public abstract class OrderUtils {
 					ClassUtils.forName("javax.annotation.Priority", OrderUtils.class.getClassLoader());
 		}
 		catch (Throwable ex) {
-			// javax.annotation.Priority not available, or present but not loadable (on JDK 6)
+			// javax.annotation.Priority not available
 			priorityAnnotationType = null;
 		}
 	}