=con #15788 Harden ClusterShardingSpec
!con #16123 Expand cluster roles support in ClusterSharding

Allow a roleOverride: Option[String] to be used when starting ClusterSharding for a given entry type. This will allow role defined clusters of ClusterSharding for entry types instead of requiring the role configuration to be all or nothing across all entry types.
Merge pull request #16202 from akka/wip-15788-harden-ClusterShardingSpec-patriknw

=con #15788 Harden ClusterShardingSpec
=per #16009 Serialize SnapshotHeader without Java serialization

* it is backwards compatible, i.e. it can read old snapshots

(cherry picked from commit 690905eac9619da91d7b1fcbc633d1fa2e411ee7)

Conflicts:
	akka-persistence/src/test/scala/akka/persistence/serialization/SerializerSpec.scala
=doc #16198 FSM extends Actor, not depends on it

The documentation incorrectly stated that FSM uses self type references
to depend on Actor, but it’s false, FSM directly extends Actor.
Merge pull request #16211 from akka/wip-16009-snapshot-header-serializer-master-patriknw

=per #16009 Serialize SnapshotHeader without Java serialization (for validation)
Merge pull request #16213 from kosii/kosii/fsm_docs_fix_#16198

=doc #16198 FSM extends Actor, not depends on it
Merge pull request #16136 from rmarsch/entryRoleOverride-#16123

ClusterSharding: Expanded cluster roles support
+doc #15542 Change FSM doc rst file to correctly specify None value for infinite timeout rather than Duration.Inf
=act #16199 fixed missing predicate delegation
Merge pull request #16240 from BPoserow/fix-fsm-timeout-docs-15542-bposerow

+doc #15542 Change FSM doc rst file to correctly specify None value for ...
Merge pull request #16248 from ktoso/port-fsm-bug-ktoso

=act #16199 fixed missing predicate delegation
=act #15991 delay sending of ACK until we have updated pendingWrite

Otherwise, the user-level actor may already have sent the next chunk before
the pendingWrite has been updated and the TcpConnection will reject it.
(cherry picked from commit 96758e6)
=tcp #15766: Workaround for Windows to detect TCP abort
(cherry picked from commit 9340215)
Merge pull request #16269 from drewhk/wip-15766-tcp-abort-win-forwardport-drewhk

=tcp #15766: Workaround for Windows to detect TCP abort
Merge pull request #16267 from drewhk/wip-15991-tcp-pendingwrite-fix-forward-port-drewhk

=act #15991 delay sending of ACK until .. (forward port)
=doc Fix wrong rst format
+act #15956 Allow _ in ActorSystem name

(cherry picked from commit 7ef1334192de6f2c0cffbb81be620cdd56110ad5)
Merge pull request #16274 from akka/wip-doc-formatting-bug-patriknw

=doc Fix wrong rst format
Merge pull request #16278 from akka/wip-15956-ActorSystem-name-master-patriknw

+act #15956 Allow _ in ActorSystem name (fwd port)