All messages that are used within the UnboundID LDAP SDK are defined in properties files and may be localized using standard Java resource bundles.
JNDI does not appear to provide any support for localization. All messages used within the API appear to be hard-coded.
The Netscape Directory SDK for Java appears to provide localization support for the string representations of LDAP result codes. All other messages used within the SDK appear to be hard-coded.