Michael,
Are you using Open JDK to run Webclipse, by any chance? If so, it looks like that may cause some issues. If possible, please install an Oracle JDK (if you haven’t already installed it) and add the following 2 lines to the eclipse.ini file, before the -vmargs line:
-vm
<em><path to Oracle JDK></em>/bin/java
Please let us know if that helps.