Using Eclipse, I can open a Java source file with an external editor by right-clicking on the file name (in the Package Explorer) and selecting Open With ... -> emacsclient.

I'm very glad to be able to do that. However, I only want to do that sometimes, not every time. Now, when I double-click on that same file name, I always automatically get the file opened in emacsclient. This is particularly annoying when I use the Open Type dialog to find a file, because in that case it's not possible to right-click and choose the default Eclipse editor.

Is there a way to make Eclipse forget that I previously opened a particular file with emacsclient, so that it can go back to the default behavior of using the regular Eclipse editor?