DATAES-793 - Upgrade to Elasticsearch 6.2.4. (#435)

Original PR: #435

README.adoc

@@ -119,7 +119,7 @@ Add the Maven dependency:
 |===
 |Spring Data Elasticsearch | Elasticsearch
 |3.2.x |6.7.2
-|3.1.x |6.2.2
+|3.1.x |6.2.4
 |3.0.x |5.5.0
 |2.1.x |2.4.0
 |2.0.x |2.2.0

pom.xml

@@ -19,7 +19,7 @@
 	<properties>
 		<commonscollections>3.2.1</commonscollections>
 		<commonslang>2.6</commonslang>
-		<elasticsearch>6.2.2</elasticsearch>
+		<elasticsearch>6.2.4</elasticsearch>
 		<log4j>2.9.1</log4j>
 		<springdata.commons>2.1.17.BUILD-SNAPSHOT</springdata.commons>
 		<java-module-name>spring.data.elasticsearch</java-module-name>

src/test/resources/test-home-dir/modules/lang-expression/plugin-descriptor.properties

@@ -22,7 +22,7 @@
 description=Lucene expressions integration for Elasticsearch
 #
 # 'version': plugin's version
-version=6.2.2
+version=6.2.4
 #
 # 'name': the plugin name
 name=lang-expression
@@ -37,7 +37,7 @@ classname=org.elasticsearch.script.expression.ExpressionPlugin
 java.version=1.8
 #
 # 'elasticsearch.version': version of elasticsearch compiled against
-elasticsearch.version=6.2.2
+elasticsearch.version=6.2.4
 ### optional elements for plugins:
 #
 #  'extended.plugins': other plugins this plugin extends through SPI

src/test/resources/test-home-dir/modules/lang-expression/plugin-security.policy

@@ -7,7 +7,7 @@
  * not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
- *    https://www.apache.org/licenses/LICENSE-2.0
+ *    http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an