Mark some methods of ChannelCredentials as internal

[murgatroid99]

This should make the ChannelCredentials classes in the two libraries have the same API.

[kjin]

Would it be possible to make all hidden methods protected, and expose them through an internal subclass? E.g.

class ChannelCredentials {
  protected _getConnectionState() {}
}

class InternalChannelCredentials {
  getConnectionState() { return this._getConnectionState(); }
}

// ... SecureChannelCredentialsImpl overrides InternalChannelCredentials

Or, we could use symbols for the hidden methods? Though, I'm not sure if TS supports exporting classes with public symbol fields.

[murgatroid99]

I don't think I like that option because it ends up requiring some typecasts that I would prefer to avoid. The Channel API accepts a generic ChannelCredentials object that the user gets from the ChannelCredentials API, and it would have to typecast it to whatever internal type to access the internal functions.

[nicolasnoble]

Right, as long as we don't have a proper system to declare friend classes, this is the best we might come up with.