presto-example-http/src/main/java/io/prestosql/plugin/example/ExampleClient.java/ExampleClient/getTableNames
class ExampleClient:    public Set<String> getTableNames(String schema)
    {
        requireNonNull(schema, "schema is null");
        Map<String, ExampleTable> tables = schemas.get().get(schema);
        if (tables == null) {
            return ImmutableSet.of();
        }
        return tables.keySet();
    }