Not sure I understand what you are trying to do. Is it something similar to this prior discussion: Re: 4.0 connections.xml encryption decryption
Anyway, since 4.0, using the our standard export/import connections facility, passwords must either be stripped out or encrypted. Similarly, if you just try to move the connections.xml between machines, we detect that and automatically strip out the passwords.
In fact, I don't add new connections from ORACLE SQL DEVELOPER. I write directly in the file connections.xml.
All configuration is filled in correctly except the password.
What you are trying to do is unsupported. The code that does the connection migration is from the JDeveloper team, and I guess that changed at some point between the JDev 11 and 12 releases. I have no idea if alternate tags exist to get the xml processor to do what you want during normal loading of connections.xml.
Who could give me this information?