eclim autocompletion (validate) cannot find all packages from maven project dependencies

Question

ENV : eclim-2.6.0, eclipse neon, What I did : Under workspace of Eclipse, I have a maven project directory. Then under maven project I run mvn eclipse:eclipse, open an vim and do :MvnRepo, and import the project with :ProjectImport proj my maven repo is at ~/.m2/repository

Start eclimd service I can get :ProjectInfo (nature is none though by default), when I try to use autocomplete, complain no required nature java, I use :ProjectNatureAdd proj java added java nature, but I found a lot of package cannot found. For example, in a test file, if I do :Validate to check syntax, imported junit cannot be resolved, and autocompletion cannot find junit package either.

I have struggle with this problem for a long time, what can I do to resolve this?