StateSnapshotRestore (Flink : 2.0-SNAPSHOT API)

All Known Implementing Classes:

CopyOnWriteStateTable, HeapPriorityQueueSnapshotRestoreWrapper, StateTable
```
@Internal
public interface StateSnapshotRestore
```
Interface to deal with state snapshot and restore of state. TODO find better name?

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`StateSnapshotKeyGroupReader`	`keyGroupReader(int readVersionHint)`	This method returns a `StateSnapshotKeyGroupReader` that can be used to restore the state on a per-key-group basis.
`StateSnapshot`	`stateSnapshot()`	Returns a snapshot of the state.

- Method Detail
  - stateSnapshot
```
@Nonnull
StateSnapshot stateSnapshot()
```
    Returns a snapshot of the state.
  - keyGroupReader
```
@Nonnull
StateSnapshotKeyGroupReader keyGroupReader(int readVersionHint)
```
    This method returns a StateSnapshotKeyGroupReader that can be used to restore the state on a per-key-group basis. This method tries to return a reader for the given version hint.
    
    Parameters:
    
    readVersionHint - the required version of the state to read.
    
    Returns:
    
    a reader that reads state by key-groups, for the given read version.