make DomainPlugins package-private

We should rather extend the plugin instantiation logic to allow non-public constructors
than making it public to be possibly invoked by users.

Signed-off-by: Peter Gafert <[email protected]>

Author: codecholeric

archunit/src/jdk9main/java/com/tngtech/archunit/core/domain/Java9DomainPlugin.java

@@ -15,16 +15,14 @@
  */
 package com.tngtech.archunit.core.domain;
 
-import com.tngtech.archunit.Internal;
 import com.tngtech.archunit.core.InitialConfiguration;
 import com.tngtech.archunit.core.PluginLoader;
 
 /**
  * Resolved via {@link PluginLoader}
  */
 @SuppressWarnings("unused")
-@Internal
-public class Java9DomainPlugin implements DomainPlugin {
+class Java9DomainPlugin implements DomainPlugin {
     @Override
     public void plugInAnnotationPropertiesFormatter(InitialConfiguration<AnnotationPropertiesFormatter> propertiesFormatter) {
         propertiesFormatter.set(AnnotationPropertiesFormatter.configure()

archunit/src/main/java/com/tngtech/archunit/core/PluginLoader.java

@@ -15,6 +15,7 @@
  */
 package com.tngtech.archunit.core;
 
+import java.lang.reflect.Constructor;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -83,7 +84,9 @@ private T create(String className) {
             try {
                 Class<?> clazz = Class.forName(className);
                 checkCompatibility(className, clazz);
-                return (T) clazz.getConstructor().newInstance();
+                Constructor<?> constructor = clazz.getDeclaredConstructor();
+                constructor.setAccessible(true);
+                return (T) constructor.newInstance();
             } catch (Exception e) {
                 throw new PluginLoadingFailedException(e, "Couldn't load plugin of type %s", className);
             }

archunit/src/main/java/com/tngtech/archunit/core/domain/Java14DomainPlugin.java

@@ -15,16 +15,14 @@
  */
 package com.tngtech.archunit.core.domain;
 
-import com.tngtech.archunit.Internal;
 import com.tngtech.archunit.core.InitialConfiguration;
 import com.tngtech.archunit.core.PluginLoader;
 
 /**
  * Resolved via {@link PluginLoader}
  */
 @SuppressWarnings("unused")
-@Internal
-public class Java14DomainPlugin implements DomainPlugin {
+class Java14DomainPlugin implements DomainPlugin {
     @Override
     public void plugInAnnotationPropertiesFormatter(InitialConfiguration<AnnotationPropertiesFormatter> propertiesFormatter) {
         propertiesFormatter.set(AnnotationPropertiesFormatter.configure()