Merge pull request #8 from marthursson/master

Hook method to add custom data to JSON event

json/classic/src/main/java/ch/qos/logback/contrib/json/classic/JsonLayout.java

@@ -219,9 +219,23 @@ protected Map toJsonMap(ILoggingEvent event) {
             }
         }
 
+        addCustomDataToJsonMap(map, event);
         return map;
     }
 
+    /**
+     * Override to add custom data to the produced JSON from the logging event.
+     * Useful if you e.g. want to include the parameter array as a separate json attribute.
+     *
+     * @param map the map for JSON serialization, populated with data corresponding to the
+     *            configured attributes. Add new entries from the event to this map to have
+     *            them included in the produced JSON.
+     * @param event the logging event to extract data from.
+     */
+    protected void addCustomDataToJsonMap(Map<String, Object> map, ILoggingEvent event) {
+        // Nothing to do in default implementation
+    }
+
     public boolean isIncludeLevel() {
         return includeLevel;
     }