I have a namespace defined as the following: 

namespace Build {

    internal const string DATA_DIR = "";
    internal const string PACKAGE_DATA_DIR = "";
    internal const string GETTEXT_PACKAGE = "vala-stacktrace";

    internal const string VERSION = "0.9";
    internal const string RELEASE_NAME = "";
    internal const string TITLE = "Vala stacktrace display";
    internal const string BINARY_NAME = "vala-stacktrace";

    // Values: Release or Debug
    internal const string BUILD = "Release";

    internal const string SOVERSION = "";
    internal const string LINKING = "shared";

    internal bool is_debug () {
        return BUILD == "Debug" ;
    }

    internal string to_string () {
        var result = new StringBuilder () ;
        result.append (" - DATA_DIR         : %s\n".printf(DATA_DIR)) ;
        result.append (" - PACKAGE_DATA_DIR : %s\n".printf(PACKAGE_DATA_DIR)) ;
        result.append (" - GETTEXT_PACKAGE : %s\n".printf(GETTEXT_PACKAGE)) ;
        result.append (" - TITLE           : %s\n".printf(TITLE)) ;
        result.append (" - VERSION         : %s\n".printf(VERSION)) ;
        result.append (" - BINARY_NAME     : %s\n".printf(BINARY_NAME)) ;
        result.append (" - BUILD           : %s\n".printf(BUILD)) ;
        result.append (" - RELEASE_NAME     : %s\n".printf(RELEASE_NAME)) ;
        result.append (" - SOVERSION       : %s\n".printf(SOVERSION)) ;
        result.append (" - LINKING         : %s\n".printf(LINKING)) ;
        return result.str ;
    }

}

And while valadoc doesn't display any of those functions, it still displays an empty Build namespace.