Why .Net IConversationStorage is Internal and not Public?

[ali-gol]

At the moment the IConversationStorage interface is internal AddOpenAIConversations registers the InMemoryConversationStorage.
I would like to register my own IConversationStorage in order to store my chat history in custom storage.

public static IServiceCollection AddOpenAIConversations(this IServiceCollection services)
{
    ArgumentNullException.ThrowIfNull(services, "services");
    services.TryAddSingleton<InMemoryStorageOptions>();
    services.TryAddSingleton<IConversationStorage, InMemoryConversationStorage>();
    services.TryAddSingleton<IAgentConversationIndex, InMemoryAgentConversationIndex>();
    return services;
}

Is there a reason why it is an internal Interface at first place?