Return per-validator rewards when querying delegator all delegations rewards

[alessio]

Closes: #3715

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.
• Wrote tests
• Updated relevant documentation (docs/)
• Added a relevant changelog entry: sdkch add [section] [stanza] [message]
• rereviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #4101 into develop will increase coverage by 0.08%.
The diff coverage is 40.9%.

@@            Coverage Diff             @@
##           develop   #4101      +/-   ##
==========================================
+ Coverage    60.12%   60.2%   +0.08%     
==========================================
  Files          211     212       +1     
  Lines        15138   15155      +17     
==========================================
+ Hits          9101    9124      +23     
+ Misses        5415    5407       -8     
- Partials       622     624       +2

[fedekunze]

LGTM

[alexanderbez]

A few things:

1. The REST client seems to perform what is defined in the issue, but the CLI is broken:

gaiacli q distr rewards cosmos16vj039cqcqu5er4229yctg2af24nu6es9uemel --chain-id=chain-EVziqe --home ./build/node0/gaiacli

panic: json: cannot unmarshal object into Go value of type []json.RawMessage

goroutine 1 [running]:
github.com/tendermint/go-amino.(*Codec).MustUnmarshalJSON(...)
	/Users/aleksbez/go/pkg/mod/github.com/tendermint/[email protected]/amino.go:445
github.com/cosmos/cosmos-sdk/x/distribution/client/cli.GetCmdQueryDelegatorRewards.func1(0xc000b76280, 0xc000bc8440, 0x1, 0x4, 0x0, 0x0)
	/Users/aleksbez/go/src/github.com/cosmos/cosmos-sdk/x/distribution/client/cli/query.go:161 +0x372
github.com/spf13/cobra.(*Command).execute(0xc000b76280, 0xc000bc8380, 0x4, 0x4, 0xc000b76280, 0xc000bc8380)
	/Users/aleksbez/go/pkg/mod/github.com/spf13/[email protected]/command.go:762 +0x465
github.com/spf13/cobra.(*Command).ExecuteC(0xc0001c8f00, 0x47ba47f, 0xc0001c8f00, 0x4b290c3)
	/Users/aleksbez/go/pkg/mod/github.com/spf13/[email protected]/command.go:852 +0x2ec
github.com/spf13/cobra.(*Command).Execute(...)
	/Users/aleksbez/go/pkg/mod/github.com/spf13/[email protected]/command.go:800
github.com/tendermint/tendermint/libs/cli.Executor.Execute(0xc0001c8f00, 0x4ef28c8, 0x2, 0xc000b0fe00)
	/Users/aleksbez/go/pkg/mod/github.com/tendermint/[email protected]/libs/cli/setup.go:89 +0x3c
main.main()
	/Users/aleksbez/go/src/github.com/cosmos/cosmos-sdk/cmd/gaia/cmd/gaiacli/main.go:110 +0x818

2. The REST client response should not include the type or value. This is because this response type is registered with Amino and probably shouldn't be.

Result:

{
    "type": "cosmos-sdk/QueryDelegatorTotalRewardsResponse",
    "value": {
        "rewards": [
            {
                "reward": [
                    {
                        "amount": "671.477500000000000000",
                        "denom": "stake"
                    }
                ],
                "validator_address": "cosmosvaloper16vj039cqcqu5er4229yctg2af24nu6esqgdw4v"
            }
        ],
        "total": [
            {
                "amount": "671.477500000000000000",
                "denom": "stake"
            }
        ]
    }
}

Expected:

{
        "rewards": [
            {
                "reward": [
                    {
                        "amount": "671.477500000000000000",
                        "denom": "stake"
                    }
                ],
                "validator_address": "cosmosvaloper16vj039cqcqu5er4229yctg2af24nu6esqgdw4v"
            }
        ],
        "total": [
            {
                "amount": "671.477500000000000000",
                "denom": "stake"
            }
        ]
    }

[alexanderbez]

@alessio almost there! The REST response looks good and the CLI (text) response looks good, but the CLI JSON response still has the type and value keys.

eg.

$ gaiacli q distr rewards cosmos17pfgtmlfrvjk4mty6mdw9jf0hjdu355uwwp25t --chain-id=chain-MKV85i --home ./build/node0/gaiacli -o json | pj

{
    "type": "cosmos-sdk/QueryDelegatorTotalRewardsResponse",
    "value": {
        "rewards": [
            {
                "validator_address": "cosmosvaloper17pfgtmlfrvjk4mty6mdw9jf0hjdu355ut64lcc",
                "reward": [
                    {
                        "denom": "stake",
                        "amount": "99.425000000000000000"
                    }
                ]
            }
        ],
        "total": [
            {
                "denom": "stake",
                "amount": "99.425000000000000000"
            }
        ]
    }
}

Why do we need to register the types? Can't they just be simply JSON encoded and decoded?

[alexanderbez]

TestedACK.