Hi all, Let's track the API behavior changes in this email thread, so as not forget about them for the next release.
ARROW-5842 <https://issues.apache.org/jira/browse/ARROW-5842>: the semantics of lastSet in ListVector changes. In the past, it refers to the next index that will be set; now it points to the last index that is actually set. ARROW-5973 <https://issues.apache.org/jira/browse/ARROW-5973>: The semantics of the get methods for VarCharVector, VarBinaryVector, and FixedSizeBinaryVector changes. If the past, if the validity bit is clear, the methods throw throws an IllegalStateException when NULL_CHECKING_ENABLED is set, or returns an empty object when the flag is not set. Now, the get methods returns a null if the validity bit is clear. Best, Liya Fan
