Migration from Elastcsearch 1.* to 2.* and boolean types

I have to migrate elasticsearch 1.3 to 2.* but the doc suggests that there is some changes with the boolean types: "They have been refactored to use numeric fielddata, with 0 for false and 1 for true". The current documents in the index store the boolean types with "true" and "false". The documentation wasn't clear enough (or I'm misreading it) but should I reindex these values to "0" and "1" before the update or I should do it afterwards.