This is a bugfix release to address mainly the following things:

#1102: This fixes mutation when used with the batched data loader instrumentation. #1090: This fixes chained instrumentation. #1072: Not consistent exception handling across strategies

The full list of changes can be found here: https://github.com/graphql-java/graphql-java/pulls?q=is%3Apr+milestone%3A9.1+is%3Aclosed