Where are the protocol mapper config options documented?

I’m using Keycloak’s Java keycloak-admin-client and I’m wanting to set up some protocol mappers for my realm’s client.

The Java API exposes this class to create a protocol mapper and then the following method to set the config options:

    ProtocolMapperRepresentation protocolMapperRep = new ProtocolMapperRepresentation();
    protocolMapperRep.setConfig(Map.of("some.mapper.config.option", "mapper-value"));

I saw a few options from another StackOverflow question here: Add protocol-mapper to keycloak using kcadm.sh

However, there has to be a better place where these are documented.

IMHO there is no documentation. I use Keycloak console (UI) and browser network console to get idea about parameters, config options and their values.

That’s what I was worried about. So if I understand correctly, you use the developer mode and create a new mapper in the browser (localhost) and inspect the request that gets sent?

Long story short, yes. Doing what Jangaraj described above worked for me. I got similar advice on Stack Overflow.

I ended up doing something like this for a user attribute mapper:

    ProtocolMapperRepresentation protocolMapper = new ProtocolMapperRepresentation();
        new HashMap<>() {
            put("jsonType.label", type);
            put("access.token.claim", "true");
            put("id.token.claim", "true");
            put("userinfo.token.claim", "true");
            put("user.attribute", claim);
            put("claim.name", claim);

It’s a real shame that there isn’t any proper documentation on this.