restore compatability for older versions

3244.vf7f977e04755 requires the agent to be upgraded in lockstep with
Jenkins to avoid remoting errors such as:

java.lang.IllegalStateException: Unable to call getName. No matching method found in [interface hudson.remoting.RemoteClassLoader$IClassLoader] for hudson.remoting.RemoteClassLoader$ClassLoaderProxy@2cdf8d8a[jdk.internal.loader.ClassLoaders$AppClassLoader@2cdf8d8a]

This restores the compatability by specifically handling a method call
to getName for the IClassLoader and returning a dummy value if the
remote version is older than 3244

src/main/java/hudson/remoting/RemoteClassLoader.java

@@ -177,6 +177,11 @@ public static ClassLoader create(@CheckForNull ClassLoader parent, @NonNull ICla
             name = proxy.getName();
         } catch(IOException ignored) {
             name = String.format(Locale.ROOT, "unknown-due-to-io-error %1$#x", System.identityHashCode(proxy));
+        } catch (IllegalStateException ignored) {
+            // IllegalStateException is thrown if the method does not exist on the remote side.
+            // TODO remove this at some point in the future when Jenkins sets the minimum remoting version to
+            // 3244.vf7f977e04755 or higher
+            name = String.format(Locale.ROOT, "upgrade-remoting-to-3244.vf7f977e04755-or-higher %1$#x", System.identityHashCode(proxy));
         }
         return new RemoteClassLoader(name, parent, proxy);
     }