Syntax Highlights Not Available in Eclipse Plugin
Problem
I associated the .ext extension with Oxygen XML Author Eclipse plugin in Eclipse but
        an .ext file opened with the Oxygen XML Author Eclipse plugin plugin does not have
        syntax highlights.
Solution
Associate an extension with Oxygen XML Author Eclipse plugin in Eclipse versions 4.5-4.35 by following these steps:
          - Associate the .extextension with the Oxygen XML Author Eclipse plugin plugin:- Open the Preferences dialog box and go to .
- Add *.extto the list of file types.
- Select *.extin the list by clicking it.
- Add Oxygen XML Author Eclipse plugin to the list of Associated editors and make it the default editor.
 
- Associate the .extextension with the Oxygen XML content type:- Open the Preferences dialog box and go to .
- Add *.extto the File associations list for the content type.
 
- Click the OK button in the Eclipse preferences dialog box.
Result: Now when an *.ext file is opened, the icon and the
            syntax highlights should be the same as for XML files opened with the Oxygen XML Author Eclipse plugin plugin.
