Fix random in TestManageAliasAndWriteAlias testIndexWithManageAliasReindex

java.lang.AssertionError: expected:<test> but was:<null>
	at org.nuxeo.elasticsearch.test.TestManageAliasAndWriteAlias.testIndexWithManageAliasReindex(TestManageAliasAndWriteAlias.java:143)

Seen here:
https://qa.nuxeo.org/jenkins/job/TestAndPush/job/ondemand-testandpush-fguillaume/480/

Possible cause is that that the HashMap to store index name for each repository should be a ConcurrentHashMap. (check other maps that are updated on reindexing with managed aliases)