JOHNZON-286 Making DefaultPropertyVisibilityStrategy non-public

According to apparent concensus among the Johnzon contributors, the class "DefaultPropertyVisibilityStrategy" should not be public anymore.

This in turn reduces the need to fix JOHNZON-276 (https://issues.apache.org/jira/browse/JOHNZON-276) by PR 44 (https://github.com/apache/johnzon/pull/44).

Signed-off-by: Markus KARG <markus@headcrashing.eu>
diff --git a/johnzon-jsonb/src/main/java/org/apache/johnzon/jsonb/DefaultPropertyVisibilityStrategy.java b/johnzon-jsonb/src/main/java/org/apache/johnzon/jsonb/DefaultPropertyVisibilityStrategy.java
index 482b957..e5a5b86 100644
--- a/johnzon-jsonb/src/main/java/org/apache/johnzon/jsonb/DefaultPropertyVisibilityStrategy.java
+++ b/johnzon-jsonb/src/main/java/org/apache/johnzon/jsonb/DefaultPropertyVisibilityStrategy.java
@@ -30,7 +30,7 @@
 import javax.json.bind.annotation.JsonbVisibility;
 import javax.json.bind.config.PropertyVisibilityStrategy;
 
-public class DefaultPropertyVisibilityStrategy implements javax.json.bind.config.PropertyVisibilityStrategy {
+class DefaultPropertyVisibilityStrategy implements javax.json.bind.config.PropertyVisibilityStrategy {
     private final ConcurrentMap<Class<?>, PropertyVisibilityStrategy> strategies = new ConcurrentHashMap<>();
 
     @Override