[Doc]Fix default value for index and bump to v.10.4.0 (logstash-plugins#927)

* Fix index default value

* Fix implementation and bump version

Author: karenzone

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 10.4.0
+ - Fixed default index value [#927](https://github.com/logstash-plugins/logstash-output-elasticsearch/pull/927)
+
 ## 10.3.3
  - [DOC] Replaced link to Elastic Cloud trial with attribute, and fixed a comma splice [#926](https://github.com/logstash-plugins/logstash-output-elasticsearch/pull/926)
 

docs/index.asciidoc

@@ -501,7 +501,7 @@ NOTE: `ilm_rollover_alias` does NOT support dynamic variable substitution as `in
 ===== `index` 
 
   * Value type is <<string,string>>
-  * Default value is `"logstash-%{+YYYY.MM.dd}"`
+  * Default value is `"logstash-%{+yyyy.MM.dd}"`
 
 The index to write events to. This can be dynamic using the `%{foo}` syntax.
 The default value will partition your indices by day so you can more easily

lib/logstash/outputs/elasticsearch/common_configs.rb

@@ -3,7 +3,7 @@
 module LogStash; module Outputs; class ElasticSearch
   module CommonConfigs
 
-    DEFAULT_INDEX_NAME = "logstash-%{+YYYY.MM.dd}"
+    DEFAULT_INDEX_NAME = "logstash-%{+yyyy.MM.dd}"
     DEFAULT_POLICY = "logstash-policy"
     DEFAULT_ROLLOVER_ALIAS = 'logstash'
 

logstash-output-elasticsearch.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name            = 'logstash-output-elasticsearch'
-  s.version         = '10.3.3'
+  s.version         = '10.4.0'
   s.licenses        = ['apache-2.0']
   s.summary         = "Stores logs in Elasticsearch"
   s.description     = "This gem is a Logstash plugin required to be installed on top of the Logstash core pipeline using $LS_HOME/bin/logstash-plugin install gemname. This gem is not a stand-alone program"