presto-spi/src/main/java/io/prestosql/spi/security/RoleGrant.java/RoleGrant/RoleGrant
class RoleGrant:    @JsonCreator
    public RoleGrant(@JsonProperty("grantee") PrestoPrincipal grantee, @JsonProperty("roleName") String roleName, @JsonProperty("grantable") boolean grantable)
    {
        this.grantee = requireNonNull(grantee, "grantee is null");
        this.roleName = requireNonNull(roleName, "roleName is null").toLowerCase(ENGLISH);
        this.grantable = grantable;
    }