private Map<String, Object> createAttributeMap() {
        final Map<String, Object> attributeMap = new HashMap<>();
        attributeMap.put(FEED.getFldName(), "TEST_FEED");
        attributeMap.put(TYPE.getFldName(), StreamTypeNames.RAW_EVENTS);
        return attributeMap;
    }
This ought to behave in a consistent way with CommonExpressionMapper
stroom-search/stroom-expression-matcher/src/test/java/stroom/expression/matcher/TestExpressionMatcher.java