Changing oraclejdk8 to openjdk8 in hopes that it will fix our Travis builds.
Changing oraclejdk8 to openjdk8 in hopes that it will fix our Travis builds.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=263837785

google/auto,google/auto,google/auto,eamonnmcmanus/auto,eamonnmcmanus/auto,eamonnmcmanus/auto