"no default signer setup" error when invoking transaction using Idemix credential - hyperledger-fabric

Question

I'm trying to setup Idemix based on the following documentation that I found:
https://hyperledger-fabric.readthedocs.io/en/release-1.4/idemix.html
https://hyperledger-fabric-ca.readthedocs.io/en/release-1.4/users-guide.html#getting-idemix-cri-certificate-revocation-information
https://hyperledger-fabric.readthedocs.io/en/release-1.4/idemixgen.html
But when invoking a transaction, i received the error below:
$ docker exec -e "CORE_PEER_LOCALMSPTYPE=idemix" -e "CORE_PEER_LOCALMSPID=Org1IdemixMSP" -e "CORE_PEER_MSPCONFIGPATH=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/users/User1#org1.example.com" cli peer chaincode query -C channel1 -n chaincode1 -c '{"Args":["query","a"]}'
Error: error getting default signer: error obtaining the default signing identity: no default signer setup
Steps that I took:
Register a user User1#org1.example.com to fabric CA fabric-ca-client register --id.name User1#org1.example.com --id.secret mysecret --id.type client --id.affiliation org1 --id.attrs role=2 -u http://localhost:7054
Enroll the user and created an idemix identity fabric-ca-client enroll --enrollment.type idemix -u http://User1#org1.example.com:mysecret#localhost:7054
Rename $USER1_DIR/msp/IssuerRevocationPublicKey to $USER1_DIR/msp/RevocationPublicKey. During transaction invocation, the name RevocationPublicKey is expected, not IssuerRevocationPublicKey
Prepare the idemix msp. I copied IssuerPublicKey and IssuerRevocationPublicKey of the CA to the msp folder. I need to rename IssuerRevocationPublicKey to RevocationPublicKey else configtxgen will complain
In configtx.yaml, add an Idemix MSP
- &Org1Idemix
Name: Org1IdemixMSP
# ID to load the MSP definition as
ID: Org1IdemixMSP
msptype: idemix
MSPDir: crypto-config/peerOrganizations/org1idemix.example.com/
Policies: &Org1IdemixMSPPolicies
Readers:
Type: Signature
Rule: "OR('Org1IdemixMSP.member')"
Writers:
Type: Signature
Rule: "OR('Org1IdemixMSP.member')"
Admins:
Type: Signature
Rule: "OR('Org1IdemixMSP.admin')"
Create genesis block, channel block, start network etc2 (as usual)
Try to query transaction and the aforementioned error appears
I did some troubleshooting and based on idemixgen documentation, I found out that I need to put a default signer into the idemix msp i.e. in the user folder. So I placed User1#org1.example.com's SignerConfig file into the user folder and rerun configtxgen. I received the following error:
Error loading MSP configuration for org: Org1IdemixMSP: unexpected EOF
Next I did some comparing with the SignerConfig generated by idemixgen and SignerConfig of User1#org1.example.com. The one generated by idemixgen cannot be opened while the other one is a .json file (shown below), so the format is different. Running configtxgen Using the SignerConfig generated by idemixgen is successful. I want to try to invoke transactions by identities generated by idemixgen but there is no way to generate an identity except for the default signer.
{
"Cred": "CkQKIK/7Slvg7laNMv8n7urCKpRN4gTZJZ7xQUyqPQ0GskWFEiCq/aRBmXlQAnSeJLXViGEHLRoztSCoHU6PDXaft+STexJECiB1dosl0QwT5dR/iNwfj0UvWZLph5U6fTMUVjYXE3W/UhIg6U+q6S9xMZhL7SHYe/v//Vhsw7X7N+93Ha4qQiWu0OIaIKcFZamTWwD5VQppZDEdxv5nr4DZAOn/S0r3gchLFG66IiD7kc8IZFRji8ub7yS5ueK8ZcLm5o+WR9a7wAx7o6fKQCogieDBP6ZS9S2R/JDVaLcAcNbtGlnF2fRS37GyoZmxko4qIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACKiArm8Pnrt+hrBAk1PD9trARpE6XVbdfXN+27uSe9r8uxCogAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAE=",
"Sk": "LwrgRX48aewbqKWrvNjo5VFfNSDIJAvdaR4brzOsnWM=",
"organizational_unit_identifier": "org1",
"enrollment_id": "User1#org1.example.com",
"credential_revocation_information": "CAESiAEKIP4MM1C0yWwgKFYPV3wokTrOHFOaEr+EPNImFraJwJ77EiBOpmBXc4rAVNta4cY32BO5JN144ofQNYnSae00o35qKxogcCBG58VCo7N2dw11Ek4+Ue/LJHWNYVhI6Qm0gb7cJ/8iIAVU47zTiMKQQu6mSSl+sp+LTL6AghqYs+ASgRFKrQSbGmgwZgIxAJRyRpR+k3SaAVRm4GM3l+zBU6V/7g73C9RQIU9kPef9XqVl0Gb+hQqrgd1HsTQ5GgIxANb6XNB+CrrQgwbt6msa0SG+aQKpSl48EeP/V7beUkshNubudBS+WjS+PRbf5aW0Nw=="
}
Repo here: https://github.com/aldredb/idemix-sample

Answer 1

I went deep with the code...
if you interested, you can find the GetIdemixMspConfig function in msp/configbuilder.go at fabric 1.4 release branch.
in this function, we can see it will attempt loading a signconf with proto type.
However, we enroll the msp with ca client cli and which returns us a json...
I searched some topic as Unable to unmarshal json to protobuf struct field
In my point of view, that proto Unmarshal will fail with json format.