If hit "Index downloads are disabled, search results may be incomplete." issue.
打开"Window" --> "Preferences" ，选中Maven
勾选上那个 "Download repository index updates on startup"
If no "Search Results"
打开"Window" ---> "Show View" ---> "Maven Repositories" ---> "Global Repositories"
选择中心仓库 "central" 右键选择 "Update Index"