The following line will evaluate to false when index.mapping.source.mode is missing but _source.mode is set.
_source.mode is the "old" way of enabling synthetic source. That said, some indices may still be using it.
This creates inconsistency as syntheticSourceSupport() gets invoked, all the while the field mapper indexes documents with the assumption that synthetic source is disabled.
The following line will evaluate to false when
index.mapping.source.modeis missing but_source.modeis set._source.modeis the "old" way of enabling synthetic source. That said, some indices may still be using it.This creates inconsistency as
syntheticSourceSupport()gets invoked, all the while the field mapper indexes documents with the assumption that synthetic source is disabled.