presto-main/src/main/java/io/prestosql/metadata/MetadataListing.java/MetadataListing/listSchemas
class MetadataListing:    public static SortedSet<String> listSchemas(Session session, Metadata metadata, AccessControl accessControl, String catalogName)
    {
        Set<String> schemaNames = ImmutableSet.copyOf(metadata.listSchemaNames(session, catalogName));
        return ImmutableSortedSet.copyOf(accessControl.filterSchemas(session.toSecurityContext(), catalogName, schemaNames));
    }