Ok, In that case, it would make sense to provide appropriate enums that allow the user of the components to be able to specify the inner protocol, i.e.

    EAP_TTLS_PAP("eap-ttls:innerProtocol=pap"),
    EAP_TTLS_MD5("eap-ttls:innerProtocol=md5"),
    EAP_TTLS_EAP_MSCHAPv2("eap-ttls:innerProtocol=eap-mschapv2"),

etc. 

According to the comments in EAPTTLSAuthenticator, the three above would be the only ones supported by default, since MSCHAPv1/2 and CHAP are not supported in Java 1.5 and earlier, but I suppose you can define their equivalents too.

Restricting the use of an EAPTTLSAuthenticator to using PAP only would be pointless because initiatives like eduroam require more than just PAP in the EAP tunnel (MD5 is popular, as is EAP-MSCHAPv2). :-)