Display thread associated with ThisIsHowItsLoaded when logging at FINEST.

Some loggers may show the thread name anyway, but /log/* in the UI at least does not.
And recent versions of Jenkins are being improved to capture lots of context in the thread name;
an unreleased improvement in Stapler includes the Jelly views being rendered.

core/src/main/java/hudson/model/RunMap.java

@@ -217,8 +217,9 @@ public final class RunMap<R extends Run<?,R>> extends AbstractLazyLoadRunMap<R>
             try {
                 R b = cons.create(d);
                 b.onLoad();
-                if (LOGGER.isLoggable(FINEST))
-                    LOGGER.log(FINEST,"Loaded " + b.getFullDisplayName(),new ThisIsHowItsLoaded());
+                if (LOGGER.isLoggable(FINEST)) {
+                    LOGGER.log(FINEST, "Loaded " + b.getFullDisplayName() + " in " + Thread.currentThread().getName(), new ThisIsHowItsLoaded());
+                }
                 return b;
             } catch (Run.InvalidDirectoryNameException x) {
                 Level lvl;