## Description
Closes: #577
This pull request contains `Canceling unbonding delegation entry` and `delegate back to previous validator`
### `Msg` Service
```protobuf=
package cosmos.staking.v1beta1;
service Msg {
// CancelUnbondingDelegation
rpc CancelUnbondingDelegation(MsgCancelUnbondingDelegation) returns (MsgCancelUnbondingDelegationResponse);
}
// MsgCancelUnbondingDelegation
message MsgCancelUnbondingDelegation {
option (gogoproto.equal) = false;
option (gogoproto.goproto_getters) = false;
string delegator_address = 1 [(cosmos_proto.scalar) = "cosmos.AddressString"];
string validator_address = 2 [(cosmos_proto.scalar) = "cosmos.AddressString"];
cosmos.base.v1beta1.Coin amount = 3 [(gogoproto.nullable) = false];
// creation_height is the height which the unbonding took place.
int64 creation_height = 4;
}
// MsgCancelUnbondingDelegationResponse
message MsgCancelUnbondingDelegationResponse{
}
```
### `Msg` Method Implementation
```go=
func (k msgServer) CancelUnbondingDelegation(goCtx context.Context, msg *types.MsgCancelUnbondingDelegation) (*types.MsgCancelUnbondingDelegationResponse, error) {
/*
// checking the unbonding delegation at creation_height
// get the unbonding delegations of delegatorAddress
if ubdEntry balance is equal to msg.Amount
remove the entry from ubd
else
update the specific entry with new balance
if len(ubd.Entries) == 0 {
k.RemoveUnbondingDelegation(ctx, ubd)
} else {
k.SetUnbondingDelegation(ctx, ubd)
}
*/
// update the delegation back to validator
// get validator
validator, found := k.GetValidator(ctx, valAddr)
if !found {
return nil, types.ErrNoValidatorFound
}
// delegate the unbonding amount to validator back
_, err = k.Keeper.Delegate(ctx, delegatorAddress, msg.Amount.Amount, types.Unbonding, validator, false)
if err != nil {
return nil, err
}
_, err := ms.Keeper.CancelUnbondingDelegation(ctx,delegatorAddress,validatorAddress,amount,creation_height)
if err != nil {
return nil, err
}
return &types.MsgCancelUnbondingDelegationResponse{}, nil
}
```
#### `cli tx` Method
```bash=
simd tx staking cancel-unbond [validator-address] [amount] [creation_height] --from [user] --chain-id [chain-id]
Example:
simd tx staking cancel-unbond cosmosvaloper1mqtyv4qux68r26mql2hjhgrvz72snjwpulq22m 100000stake 10280 --from test1 --chain-id test-chain
```
---
### Author Checklist
*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*
I have...
- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed
### Reviewers Checklist
*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*
I have...
- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)
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