in src/main/java/software/amazon/msk/auth/iam/internals/IAMSaslClient.java [63:72]
public IAMSaslClient(@NonNull String mechanism,
@NonNull CallbackHandler cbh,
@NonNull String serverName,
@NonNull SignedPayloadGenerator payloadGenerator) {
this.mechanism = mechanism;
this.cbh = cbh;
this.serverName = serverName;
this.payloadGenerator = payloadGenerator;
setState(State.SEND_CLIENT_FIRST_MESSAGE);
}