presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/security/RaptorSecurityConfig.java/RaptorSecurityConfig/getSecuritySystem
class RaptorSecurityConfig:    @NotNull
    @Pattern(regexp = "none|file|read-only", message = "must be either none, file or read-only")
    public String getSecuritySystem()
    {
        return securitySystem;
    }