[TEST] fix RequestConvertersTests failure

[tlfeng]

Issue #, if available:
#23

[Update: There is another approach to deal with the failure, see issue #52]
There are 4 flaky tests failure in "REST Hight Level Client Tests" (Gradle Task :client:rest-high-level:test)

> Task :client:rest-high-level:test

REPRODUCE WITH: ./gradlew ':client:rest-high-level:test' --tests "org.elasticsearch.client.RequestConvertersTests.testSourceExistsWithType" -Dtests.seed=6441E51410EE961B -Dtests.security.manager=true -Dtests.locale=es-US -Dtests.timezone=SystemV/MST7 -Druntime.java=15

org.elasticsearch.client.RequestConvertersTests > testSourceExistsWithType FAILED
    java.lang.AssertionError: expected:<{realtime=false, refresh=true}> but was:<{realtime=false}>
        at __randomizedtesting.SeedInfo.seed([6441E51410EE961B:D80B1368D804414D]:0)
        at org.junit.Assert.fail(Assert.java:88)
        at org.junit.Assert.failNotEquals(Assert.java:834)
        at org.junit.Assert.assertEquals(Assert.java:118)
        at org.junit.Assert.assertEquals(Assert.java:144)
        at org.elasticsearch.client.RequestConvertersTests.doTestSourceExists(RequestConvertersTests.java:218)
        at org.elasticsearch.client.RequestConvertersTests.testSourceExistsWithType(RequestConvertersTests.java:172)

REPRODUCE WITH: ./gradlew ':client:rest-high-level:test' --tests "org.elasticsearch.client.RequestConvertersTests.testGetSource" -Dtests.seed=6441E51410EE961B -Dtests.security.manager=true -Dtests.locale=es-US -Dtests.timezone=SystemV/MST7 -Druntime.java=15

org.elasticsearch.client.RequestConvertersTests > testGetSource FAILED
    java.lang.AssertionError: expected:<{routing=bdpSOmeC, preference=haod, refresh=true}> but was:<{routing=bdpSOmeC, preference=haod}>
        at __randomizedtesting.SeedInfo.seed([6441E51410EE961B:FE48ED1D9D674ADC]:0)
        at org.junit.Assert.fail(Assert.java:88)
        at org.junit.Assert.failNotEquals(Assert.java:834)
        at org.junit.Assert.assertEquals(Assert.java:118)
        at org.junit.Assert.assertEquals(Assert.java:144)
        at org.elasticsearch.client.RequestConvertersTests.doTestGetSource(RequestConvertersTests.java:256)
        at org.elasticsearch.client.RequestConvertersTests.testGetSource(RequestConvertersTests.java:176)

REPRODUCE WITH: ./gradlew ':client:rest-high-level:test' --tests "org.elasticsearch.client.RequestConvertersTests.testMultiGet" -Dtests.seed=6441E51410EE961B -Dtests.security.manager=true -Dtests.locale=es-US -Dtests.timezone=SystemV/MST7 -Druntime.java=15

org.elasticsearch.client.RequestConvertersTests > testMultiGet FAILED
    java.lang.AssertionError: expected:<{refresh=true}> but was:<{}>
        at __randomizedtesting.SeedInfo.seed([6441E51410EE961B:538FF24A8A03B08C]:0)
        at org.junit.Assert.fail(Assert.java:88)
        at org.junit.Assert.failNotEquals(Assert.java:834)
        at org.junit.Assert.assertEquals(Assert.java:118)
        at org.junit.Assert.assertEquals(Assert.java:144)
        at org.elasticsearch.client.RequestConvertersTests.testMultiGet(RequestConvertersTests.java:305)

REPRODUCE WITH: ./gradlew ':client:rest-high-level:test' --tests "org.elasticsearch.client.RequestConvertersTests.testSourceExists" -Dtests.seed=6441E51410EE961B -Dtests.security.manager=true -Dtests.locale=es-US -Dtests.timezone=SystemV/MST7 -Druntime.java=15

org.elasticsearch.client.RequestConvertersTests > testSourceExists FAILED
    java.lang.AssertionError: expected:<{routing=OlPIq, refresh=true}> but was:<{routing=OlPIq}>
        at __randomizedtesting.SeedInfo.seed([6441E51410EE961B:A1A97D003C3A0640]:0)
        at org.junit.Assert.fail(Assert.java:88)
        at org.junit.Assert.failNotEquals(Assert.java:834)
        at org.junit.Assert.assertEquals(Assert.java:118)
        at org.junit.Assert.assertEquals(Assert.java:144)
        at org.elasticsearch.client.RequestConvertersTests.doTestSourceExists(RequestConvertersTests.java:218)
        at org.elasticsearch.client.RequestConvertersTests.testSourceExists(RequestConvertersTests.java:167)

Description of changes:

• Remove the tests of validating refresh parameter in getSourceRequest and multiGetRequest

The PR aims to fix the unit tests in class RequestConvertersTests

The failure is due to the removal of x-pack security (PR #16), where "refresh" parameter is removed from several kinds of requests, such as getRequest, getSourceRequest and multiGetRequest (commit)

Testing:

$ ./gradlew ':client:rest-high-level:test' --tests "org.elasticsearch.client.RequestConvertersTests"
=======================================
Elasticsearch Build Hamster says Hello!
  Gradle Version        : 6.6.1
  OS Info               : Mac OS X 10.16 (x86_64)
  JDK Version           : 14 (AdoptOpenJDK)
  JAVA_HOME             : /Library/Java/JavaVirtualMachines/adoptopenjdk-14.jdk/Contents/Home
  Random Testing Seed   : ED42825F8526BABC
  In FIPS 140 mode      : false
=======================================

> Task :client:rest-high-level:compileTestJava
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.

BUILD SUCCESSFUL in 7s
50 actionable tasks: 2 executed, 48 up-to-date

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[harold-wang]

Tianli, please do not remove the refresh, this issue is fixed in later version, here is reference:
https://github.com/elastic/elasticsearch/blob/3f9f0075451707d040e9074a4f72bab68b839faa/client/rest-high-level/src/main/java/org/elasticsearch/client/RequestConverters.java#L280

[tlfeng]

I agree it's a not a good approach to fix the test, we'd better hold this PR on.

[tlfeng]

The same test failure is resolved by PR #54, so close this PR.