import typing


def _get_import_names_in_manifest(manifest: typing.Dict) -> typing.List[str]:
    """Gets all the import names in the manifest.

    The manifest should have an import_specification field whose values are
    dicts and have an import_name field.

    Args:
        manifest: The manifest as a dict.

    Returns:
        List of import names in the manifest each as a string.
    """
    return [
        spec.get('import_name')
        for spec in manifest.get('import_specifications', [])
    ]