From d3dff6659b93df836268bf13a26be18b076365f0 Mon Sep 17 00:00:00 2001
From: Tanguy Leroux <tlrx.dev@gmail.com>
Date: Tue, 30 Aug 2016 10:10:08 +0200
Subject: [PATCH] Returns empty set of filters in MonitoringIndexNameResolver
 and fix tests

Original commit: elastic/x-pack-elasticsearch@e901347de9accf18c5267955badbf76d97a14b43
---
 .../agent/resolver/MonitoringIndexNameResolver.java          | 5 +++--
 .../agent/resolver/MonitoringIndexNameResolverTestCase.java  | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/elasticsearch/x-pack/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolver.java b/elasticsearch/x-pack/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolver.java
index 6b1cd237e8e..805531549b2 100644
--- a/elasticsearch/x-pack/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolver.java
+++ b/elasticsearch/x-pack/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolver.java
@@ -23,6 +23,7 @@ import org.joda.time.format.DateTimeFormat;
 import org.joda.time.format.DateTimeFormatter;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.Locale;
 import java.util.Set;
 import java.util.function.Function;
@@ -108,11 +109,11 @@ public abstract class MonitoringIndexNameResolver<T extends MonitoringDoc> {
 
     /**
      * @return the filters used when rendering the document.
-     * If null or empty, no filtering is applied.
+     * If empty, no filtering is applied.
      */
     public Set<String> filters() {
         // No filtering by default
-        return null;
+        return Collections.emptySet();
     }
 
     protected abstract void buildXContent(T document, XContentBuilder builder, ToXContent.Params params) throws IOException;
diff --git a/elasticsearch/x-pack/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolverTestCase.java b/elasticsearch/x-pack/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolverTestCase.java
index 2a8d0961ab9..d6826919367 100644
--- a/elasticsearch/x-pack/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolverTestCase.java
+++ b/elasticsearch/x-pack/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/agent/resolver/MonitoringIndexNameResolverTestCase.java
@@ -161,7 +161,7 @@ public abstract class MonitoringIndexNameResolverTestCase<M extends MonitoringDo
         };
         assertThat("source must contains default fields", sourceFields.keySet(), hasItems(commons));
 
-        if (fields != null) {
+        if (fields != null && fields.isEmpty() == false) {
             for (String field : fields) {
                 assertSourceField(field, sourceFields);
             }