Bug 208098 [Markers] All content provider needs a type field
As All shows everything the type column would be very useful for filtering.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/provisional/views/markers/MarkerEntry.java
*/
	public boolean isConcrete() {
		return true;
	}
	/**
	 * Set the category to markerCategory.
	 * 
	 * @param markerCategory
	 */
	public void setCategory(MarkerCategory markerCategory) {
		category = markerCategory;
	}
	/**
	 * Get the category of the receiver.
	 * @return {@link MarkerCategory}
	 */
	public MarkerCategory getCategory() {
		return category;
	}
	/**
	 * Set the marker for the receiver.
	 * @param marker The marker to set.
	 */
	public void setMarker(IMarker marker) {
		this.marker = marker;
		attributeCache.clear();
		collationKeys.clear();
	}
}