#1685 - Add support for MetaCounterMetrics and refactor DefaultServerCache to use them

src/main/java/io/ebean/cache/ServerCacheManager.java

@@ -1,5 +1,7 @@
 package io.ebean.cache;
 
+import io.ebean.meta.MetricVisitor;
+
 import java.util.List;
 
 /**
@@ -7,6 +9,11 @@ import java.util.List;
  */
 public interface ServerCacheManager {
 
+  /**
+   * Visit the metrics for all the server caches.
+   */
+  void visitMetrics(MetricVisitor visitor);
+
   /**
    * Return true if the L2 caching is local.
    * <p>