Upgrade to ES 6.7

[jinsoor-amzn]

Description of changes:

1. Upgrade to ES 6.7.1 and Gradle 5.2.1 (upstream Gradle version used by ES 6.7)

2. Scheduler.schedule has been deprecated.
   Scheduler.ScheduledFuture<?> schedule(TimeValue delay, String executor, Runnable command) has been deprecated and replace to ScheduledCancellable schedule(Runnable command, TimeValue delay, String executor). Related: elastic/elasticsearch@68ed72b#diff-0e2c2d1682285e7920440dbc4a5a49bf

3. Client RetryTimeout is removed.
   This was being used in the unit test in Alerting and it is not longer supported. Related elastic/elasticsearch@99192e7#diff-ffbc192f9ee093f558b3b55dcdc2d63f

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ghost]

Should we increase the connect timeout as well?

[jinsoor-amzn]

What connect timeout do you mean? Do you mean CLIENT_SOCKET_TIMEOUT? That is already at 10 min. I don't know if we need to increase it.

[mihirsoni]

@jinsoor-amzn Could you update the result of Integration tests ?

[jinsoor-amzn]

This is the output of the ./gradlew build.

Starting a Gradle Daemon, 1 incompatible Daemon could not be reused, use --status for details

> Configure project :alerting
=======================================
Elasticsearch Build Hamster says Hello!
  Gradle Version        : 5.2.1
  OS Info               : Mac OS X 10.13.6 (x86_64)
  JDK Version           : 12 (Oracle Corporation 12 [Java HotSpot(TM) 64-Bit Server VM 12+33])
  JAVA_HOME             : /Library/Java/JavaVirtualMachines/jdk-12.jdk/Contents/Home
  Random Testing Seed   : 454C70B1B0BABEBA
=======================================

> Task :alerting-notification:compileJava
Note: /Users/jinsoor/ws/opensource/alerting/notification/src/main/java/com/amazon/opendistroforelasticsearch/alerting/destination/Notification.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

> Task :alerting:unitTest
==> Test Info: seed=454C70B1B0BABEBA; jvms=2; suites=4
==> Test Summary: 4 suites, 17 tests

> Task :alerting:integTestRunner
==> Test Info: seed=454C70B1B0BABEBA; jvm=1; suites=4
==> Test Summary: 4 suites, 69 tests

> Task :alerting-notification:test
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.easymock.cglib.core.ReflectUtils$1 (file:/Users/jinsoor/.gradle/caches/modules-2/files-2.1/org.easymock/easymock/4.0.1/26f1c39bd323b6ac7fe0c4c8e33bfdffcdde03a2/easymock-4.0.1.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
WARNING: Please consider reporting this to the maintainers of org.easymock.cglib.core.ReflectUtils$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

Deprecated Gradle features were used in this build, making it incompatible with Gradle 6.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/5.2.1/userguide/command_line_interface.html#sec:command_line_warnings

BUILD SUCCESSFUL in 4m 2s
51 actionable tasks: 51 executed

[mihirsoni]

@jinsoor-amzn Thanks for the details.

Changes LGTM !!

[lucaswin-amzn]

LGTM!
Thanks for the change!