Bug 126779 [IDE] Removed deprecated project capabilities API and implementation
It was created then deprecated before 2.0 shipped. As has never been API and we don't use it we should delete it.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/registry/Capability.java
}
    /**
     * Returns the nature descriptor or <code>null</code> if
     * none exist.
     */
    public IProjectNatureDescriptor getNatureDescriptor() {
        return natureDescriptor;
    }
    public String getNatureId() {
        return natureId;
    }
    /* (non-Javadoc)
     * Method declared on IAdaptable.
     */
    public Object getAdapter(Class adapter) {
        if (adapter == IWorkbenchAdapter.class)
            return this;
        else
            return null;
    }
    public String getCategoryPath() {
        if (element == null)
            return ""; 
        else
            return element.getAttribute(ATT_CATEGORY);
    }
    /**
     * Returns a new instance of the capability install
     * wizard. Caller is responsible for calling the init
     * method. If the wizard cannot be created, <code>null</code>