improve dynamic config support for ValidConnectionChecker

src/main/java/com/alibaba/druid/pool/DruidDataSourceStatLogger.java

@@ -17,9 +17,17 @@ package com.alibaba.druid.pool;
 
 import java.util.Properties;
 
+/**
+ * @author wenshao<szujobs@hotmail.com>
+ * @since 0.2.19
+ */
 public interface DruidDataSourceStatLogger {
 
     void log(DruidDataSourceStatValue statValue);
-    
+
+    /**
+     * @param properties
+     * @since 0.2.21
+     */
     void configFromProperties(Properties properties);
 }