Stream.concat only accepts 2 parameters. Streams.concat on the other hand
accepts any number of parameters.
Moving to Streams.concat for all uses (2 or more) makes sense for uniformity
and convenience reasons.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=179716648
Also adds a mechanism to ensure that fee extensions are included when custom
pricing logic adds a custom fee, and fixes up the domain restore flow to
properly use the restore price.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=142715136