These files contain settings such as:
- repository information;
- information about the Eclipse project;
- project-specific Eclipse settings;
- settings used by various tools;
- user settings.
Repositories shared by a team typically have only files that are useful to the entire team or multiple people. Deciding whether or not to version these files should therefore consider avoiding files that contain information about the developer environment (absolute directory paths, user names, etc.), optional tool configurations, or user preferences, unless these information is necessarily standardized for the whole team. Generally, all of these files are text files, so you can inspect them to see if there is some of this "personal" information in them.
It is also considered good practice to avoid files that are automatically generated or that are often unnecessarily modified (for example, a tool could insert timestamp from when it was last run). >
IDE is often considered a personal choice by the developer, so many teams choose not to release specific files from an IDE (in this case, Eclipse).
I have no experience with Java to indicate exactly what files contain what.