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 String getAttributeValue(String attribute, String defaultValue) {
		if (!attributeCache.containsKey(attribute))
			attributeCache.put(attribute, marker.getAttribute(attribute,
					defaultValue));
		return (String) attributeCache.get(attribute);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.provisional.views.markers.MarkerItem#getChildren()
	 */
	public MarkerItem[] getChildren() {
		return MarkerSupportInternalUtilities.EMPTY_MARKER_ITEM_ARRAY;
	}
	/**
	 * Get the CollationKey for the string attribute.
	 * 
	 * @param attribute
	 * @param defaultValue
	 *            the defaultValue if the value is not set
	 * @return CollationKey
	 */ 
	public CollationKey getCollationKey(String attribute, String defaultValue) {
		if (collationKeys.containsKey(attribute))
			return (CollationKey) collationKeys.get(attribute);
		String attributeValue = getAttributeValue(attribute, defaultValue);
		if (attributeValue.length() == 0)
			return MarkerSupportInternalUtilities.EMPTY_COLLATION_KEY;
		CollationKey key = Collator.getInstance().getCollationKey(