// Send challenge.
AnnounceMessage.Version requestedVersion = AnnounceMessage.Version.newBuilder()
.setMajorVersion(PROTOCOL_VERSION_MAJOR)
.setMinorVersion(PROTOCOL_VERSION_MINOR)
.build();
InitMessage init = InitMessage.newBuilder()
.setBuildId(0)
.setLogin(InitMessage.LoginType.authenticatedLogin)
.setRequestedVersion(requestedVersion)
.setClientUserData(ByteString.copyFromUtf8(scramAuth.executeStep1("test9999")))
.build();