Prefer Javamelody's own configuration constants

Change-Id: I42910d0c9838d188a01b57c63df244e3ccf5c2d9
diff --git a/src/main/java/com/googlesource/gerrit/plugins/javamelody/GerritMonitoringFilter.java b/src/main/java/com/googlesource/gerrit/plugins/javamelody/GerritMonitoringFilter.java
index b3206d7..0afe8fd 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/javamelody/GerritMonitoringFilter.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/javamelody/GerritMonitoringFilter.java
@@ -36,6 +36,7 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import net.bull.javamelody.MonitoringFilter;
+import net.bull.javamelody.Parameter;
 import net.bull.javamelody.internal.common.HttpParameter;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -80,10 +81,10 @@
 
   static class JavamelodyFilter extends MonitoringFilter {
     private static final String JAVAMELODY_PREFIX = "javamelody";
-    private static final String HTTP_TRANSFORM_PATTERN = "http-transform-pattern";
+    private static final String HTTP_TRANSFORM_PATTERN = Parameter.HTTP_TRANSFORM_PATTERN.getCode();
     private static final String GLOBAL_HTTP_TRANSFORM_PATTERN =
         String.format("%s.%s", JAVAMELODY_PREFIX, HTTP_TRANSFORM_PATTERN);
-    private static final String STORAGE_DIR = "storage-directory";
+    private static final String STORAGE_DIR = Parameter.STORAGE_DIRECTORY.getCode();
     private static final String GLOBAL_STORAGE_DIR =
         String.format("%s.%s", JAVAMELODY_PREFIX, STORAGE_DIR);
     private static final String PROMETHEUS_BEARER_TOKEN = "prometheusBearerToken";