This was a surprisingly involved change. Some of the difficulties included
java.util.Optional purposely not being Serializable (so I had to move a
few Optionals in mapreduce classes to @Nullable) and having to add the Truth
Java8 extension library for assertion support.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171863777
This should have been getting turned into an InvalidHostNameException, but
wasn't. I've added tests for HostFlowUtils verifying the correct behavior for
this. Idn.toASCII() can throw IllegalArgumentException for some combinations
of input, including hostnames with a leading hyphen, so the call should be
inside the try block that turns IAEs into InvalidHostNameExceptions.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=139373849