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