Our internal tool found
HADOOP-15523 breaks public API compatibility:
|1||Field HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_SECS has been renamed to HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_KEY.||Recompilation of a client program may be terminated with the message: cannot find variable HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_SECS in CommonConfigurationKeysPublic.|
|2||Field HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_SECS_DEFAULT has been renamed to HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_DEFAULT.||Recompilation of a client program may be terminated with the message: cannot find variable HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_SECS_DEFAULT in CommonConfigurationKeysPublic.|
HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_SECS_DEFAULT is used to instantiate a variable in ShellBasedGroupsMapping objects, and since almost all applications requires groups mapping, this can cause runtime error if application loads multiple versions of Hadoop library.
IMO this is a blocker for 3.2.0