I gather you are referring to the slf4j jar that shows up nested under the 'Gradle DSLD Support' in package/project explorer?
These entries are added to provide some code-completion support for editing .gradle files. They are jars that are either part-of or used by Gradle. These files are needed for Groovy Eclipse to be able to work with your .gradle scripts inside your project.
We know that conceptually it is really wrong to have these on your project's classpath, they should only be on the classpath for the build scripts. Unfortunately Eclipse projects don't have any mechanism to attach different classpaths to some files in a project. There can be only one classpath per Eclipse project.
You can avoid these entries getting added by disabling 'DSL support' on your project.
You can enable/disable this option when you import your project by unchecking the option 'Enable DSL Support' in the import wizard.
Or, you can also disable it after import via the project context menu at 'Gradle >> Disable DSL Support'.
After Disabling DSL support you will still be able to edit your .gradle scripts in STS, but you will get fewer code-completions in the editor.
Last edited by Kris De Volder; Jan 7th, 2013 at 02:36 PM.
Kris De Volder -- SpringSource