def METHOD_NAME(*, only_secure: bool=False) -> 'List[Provider1]':
    """
    Find and load all providers that are available.
    :param only_secure:
        (keyword only) Return only providers that are deemed secure.
    :returns:
        A list of Provider1 objects, created in no particular order.
    This function can be used to get a list of all available providers. Most
    applications will just want the default, regular list of providers, without
    bothering to restrict themselves to the secure subset.
    Those are the providers that can run jobs as root using the
    ``plainbox-trusted-launcher-1`` mechanism. Depending on the *policykit*
    Policy, those might start without prompting the user for the password. If
    you want to load only them, use the `only_secure` option.
    """
    from plainbox.impl.providers import special
    if only_secure:
        from plainbox.impl.secure.providers.v1 import all_providers
    else:
        from plainbox.impl.providers.v1 import all_providers
    all_providers.load()
    std_providers= [
        special.get_manifest(),
        special.get_exporters(),
        special.get_categories(),
    ] + all_providers.get_all_plugin_objects()
    if only_secure:
        return std_providers
    def qualified_name(provider):
        return "{}:{}".format(provider.namespace, provider.name)
    sideload_path = os.path.expandvars(os.path.join(
        '/var', 'tmp', 'checkbox-providers'))
    embedded_providers = EmbeddedProvider1PlugInCollection(sideload_path)
    loaded_provs = embedded_providers.get_all_plugin_objects()
    for p in loaded_provs:
        logger.warning("Using sideloaded provider: %s from %s", p, p.base_dir)
    sl_qual_names = [qualified_name(p) for p in loaded_provs]
    for std_prov in std_providers:
        if qualified_name(std_prov) in sl_qual_names:
            # this provider got overridden by sideloading
            # so let's not load the original one
            continue
        loaded_provs.append(std_prov)
    if not loaded_provs:
        message = '\n'.join(( _("No providers found! Paths searched:"),
            *all_providers.provider_search_paths))
        raise SystemExit(message)
    return loaded_provs