[AMBARI-24652] Ambari metrics collector failed to show data for custom metrics (apappu) (#19)

diff --git a/ambari-metrics-timelineservice/src/main/java/org/apache/ambari/metrics/core/timeline/discovery/TimelineMetricMetadataManager.java b/ambari-metrics-timelineservice/src/main/java/org/apache/ambari/metrics/core/timeline/discovery/TimelineMetricMetadataManager.java
index 7c6fce5..aa8c88a 100644
--- a/ambari-metrics-timelineservice/src/main/java/org/apache/ambari/metrics/core/timeline/discovery/TimelineMetricMetadataManager.java
+++ b/ambari-metrics-timelineservice/src/main/java/org/apache/ambari/metrics/core/timeline/discovery/TimelineMetricMetadataManager.java
@@ -649,10 +649,6 @@
       }
     }
 
-    if ( StringUtils.isNotEmpty(appId) && !(appId.equals("HOST") || appId.equals("FLUME_HANDLER"))) { //HACK.. Why??
-      appId = appId.toLowerCase();
-    }
-
     if (hasWildCard(instanceId) || hasWildCard(appId) || hostNameHasWildcard || metricNameHasWildcard) {
       try {
         List<TimelineMetricMetadata> metricMetadataFromStore = hBaseAccessor.scanMetricMetadataForWildCardRequest(metricNames,