8023245: Enhance Beans decoding

Reviewed-by: art, skoivu, alanb

src/share/classes/com/sun/beans/decoder/DocumentHandler.java

@@ -29,6 +29,7 @@ import com.sun.beans.finder.ClassFinder;
 import java.beans.ExceptionListener;
 
 import java.io.IOException;
+import java.io.StringReader;
 
 import java.lang.ref.Reference;
 import java.lang.ref.WeakReference;
@@ -245,6 +246,14 @@ public final class DocumentHandler extends DefaultHandler {
         this.objects.add(object);
     }
 
+    /**
+     * Disables any external entities.
+     */
+    @Override
+    public InputSource resolveEntity(String publicId, String systemId) {
+        return new InputSource(new StringReader(""));
+    }
+
     /**
      * Prepares this handler to read objects from XML document.
      */