presto-mongodb/src/main/java/io/prestosql/plugin/mongodb/MongoClientConfig.java/MongoClientConfig/buildCredentials
class MongoClientConfig:    private List<MongoCredential> buildCredentials(Iterable<String> userPasses)
    {
        ImmutableList.Builder<MongoCredential> builder = ImmutableList.builder();
        for (String userPassCollection : userPasses) {
            int lastIndex = userPassCollection.lastIndexOf('@');
            checkArgument(lastIndex > 0, "Invalid Credential format. Requires user:password@collection");
            String userPass = userPassCollection.substring(0, lastIndex);
            String collection = userPassCollection.substring(lastIndex + 1);

            int firstIndex = userPass.indexOf(':');
            checkArgument(firstIndex > 0, "Invalid Credential format. Requires user:password@collection");
            String user = userPass.substring(0, firstIndex);
            String password = userPass.substring(firstIndex + 1);

            builder.add(createCredential(user, collection, password.toCharArray()));
        }
        return builder.build();
    }