Remove usages of deprecated (in Java 9 and above) Class#newInstance (#5483)

* Remove usages of deprecated (in Java 9 and above) `Class#newInstance`

* Improve catching of InvocationTargetException

* Use AssertionError where appropriate

core/src/main/java/hudson/ClassicPluginStrategy.java

@@ -31,6 +31,7 @@ import hudson.util.CyclicGraphDetector;
 import hudson.util.CyclicGraphDetector.CycleDetectedException;
 import hudson.util.IOUtils;
 import hudson.util.MaskingClassLoader;
+import java.lang.reflect.InvocationTargetException;
 import jenkins.ClassLoaderReflectionToolkit;
 import jenkins.ExtensionFilter;
 import jenkins.plugins.DetachedPluginsUtil;
@@ -379,14 +380,14 @@ public class ClassicPluginStrategy implements PluginStrategy {
             } else {
                 try {
                     Class<?> clazz = wrapper.classLoader.loadClass(className);
-                    Object o = clazz.newInstance();
+                    Object o = clazz.getDeclaredConstructor().newInstance();
                     if(!(o instanceof Plugin)) {
                         throw new IOException(className+" doesn't extend from hudson.Plugin");
                     }
                     wrapper.setPlugin((Plugin) o);
                 } catch (LinkageError | ClassNotFoundException e) {
                     throw new IOException("Unable to load " + className + " from " + wrapper.getShortName(),e);
-                } catch (IllegalAccessException | InstantiationException e) {
+                } catch (NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
                     throw new IOException("Unable to create instance of " + className + " from " + wrapper.getShortName(),e);
                 }
             }