presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/HivePrincipal.java/HivePrincipal/HivePrincipal
class HivePrincipal:    @JsonCreator
    public HivePrincipal(@JsonProperty("type") PrincipalType type, @JsonProperty("name") String name)
    {
        this.type = requireNonNull(type, "type is null");
        requireNonNull(name, "name is null");
        if (type == PrincipalType.USER) {
            // In Hive user names are case sensitive
            this.name = name;
        }
        else if (type == PrincipalType.ROLE) {
            // In Hive role names are case insensitive
            this.name = name.toLowerCase(ENGLISH);
        }
        else {
            throw new IllegalArgumentException("Unsupported type: " + type);
        }
    }