Support "optional=true" parameter for @Extension to logging exceptions at FINE

level (instead of WARNING) for any class loading problems reading the extension.
Also move up to sezpoz 1.7 and remove catch block for LinkageError in
ExtensionFinder.. sezpoz should now throw only InstantiationException.


git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@30963 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/Extension.java

@@ -1,7 +1,7 @@
 /*
  * The MIT License
  *
- * Copyright (c) 2004-2009, Sun Microsystems, Inc.
+ * Copyright (c) 2004-2010, Sun Microsystems, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -78,4 +78,10 @@ public @interface Extension {
      * @since 1.306
      */
     double ordinal() default 0;
+
+    /**
+     * If an extension is optional, don't log any class loading errors when reading it.
+     * @since 1.358
+     */
+    boolean optional() default false;
 }