Luca Cavanna 8a412c6a26
Ensure MapperService#getAllMetaFields elements order is deterministic (#36739)
MapperService#getAllMetaFields returns an array, which is created out of
an `ObjectHashSet`. Such set does not guarantee deterministic hash
ordering. The array returned by its toArray may be sorted differently
at each run. This caused some repeatability issues in our tests (see #29080)
as we pick random fields from the array of possible metadata fields,
but that won't be repeatable if the input array is sorted differently at
every run. Once setting the tests seed, hppc picks that up and the sorting is
deterministic, but failures don't repeat with the seed that gets printed out
originally (as a seed was not originally set).
See also https://issues.carrot2.org/projects/HPPC/issues/HPPC-173.

With this commit, we simply create a static sorted array that is used for
`getAllMetaFields`. The change is in production code but really affects
only testing as the only production usage of this method was to iterate
through all values when parsing fields in the high-level REST client code.
Anyways, this seems like a good change as returning an array would imply
that it's deterministically sorted.
2018-12-18 10:43:14 +01:00
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