Mork,
The line said Content assist, as-you-type validation, syntax highlighting …, as-you-type applies to the validation, not the content assist.
Having said that, the stack overflow suggestion does work for Java in MyEclipse, so if that’s what you were looking for, going to Window > Preferences > Java > Editor > Content Assist and changing the Auto activation triggers for Java to @abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ._
will do it for you. Since the Java support in Eclipse isn’t really designed to activate on any key press, you might find some invalid / inefficient suggestions being presented at times, do let us know how this works for you.
If you were looking for this support in other file types, for example, JavaScript, HTML or TypeScript, we do have much better support for as-you-type content assist, available if you install CodeMix (free for MyEclipse Pro and higher customers).
Do let us know what editors you’d like to see this in and we’ll be able to assist further.